Easy 4 digit LED display

pxgator · May 18, 2017

The TM1637 LED display is widely available, cheap, and an easy way to add a four
digit LED display to a PICAXE project. Borrowing code from the link below I wrote
a version which runs much faster and the code size is reduced. It has been tested from
4 to 32 mhz on M2 parts and also at 64 mhz on X2 parts. The code could be made
to run even faster by converting the subroutines to macros.

http://www.picaxeforum.co.uk/showthread.php?27463-Grove-Catalex-4-digit-7-segment-displays-(TM1637)&highlight=tm1637

Code:

[color=Green];TM1637_test.bas[/color]

[color=Navy]#picaxe [/color][color=Black]08m2[/color]

[color=Green];segment data for TM1637
     ;(  0   1   2   3   4   5   6   7   8   9   A   b   C   d   E   F  dash blank)[/color]
[color=Blue]DATA [/color][color=Navy]0[/color][color=Black],[/color][color=Blue]([/color][color=Navy]$3f[/color][color=Black],[/color][color=Navy]$06[/color][color=Black],[/color][color=Navy]$5b[/color][color=Black],[/color][color=Navy]$4f[/color][color=Black],[/color][color=Navy]$66[/color][color=Black],[/color][color=Navy]$6d[/color][color=Black],[/color][color=Navy]$7d[/color][color=Black],[/color][color=Navy]$07[/color][color=Black],[/color][color=Navy]$7f[/color][color=Black],[/color][color=Navy]$6f[/color][color=Black],[/color][color=Navy]$77[/color][color=Black],[/color][color=Navy]$7c[/color][color=Black],[/color][color=Navy]$39[/color][color=Black],[/color][color=Navy]$5e[/color][color=Black],[/color][color=Navy]$79[/color][color=Black],[/color][color=Navy]$71[/color][color=Black], [/color][color=Navy]$40[/color][color=Black], [/color][color=Navy]$00[/color][color=Blue])[/color]


[color=Green];for TM1637[/color]
[color=Blue]symbol dio [/color][color=DarkCyan]= [/color][color=Blue]C.1                        [/color][color=Green];TM1637 data pin to 08m2 leg 6[/color]
[color=Blue]symbol clk [/color][color=DarkCyan]= [/color][color=Blue]C.2                        [/color][color=Green];TM1637 clock pin to 08m2 leg 5[/color]
[color=Blue]symbol  [/color][color=Purple]D3 [/color][color=DarkCyan]= [/color][color=Purple]b2[/color]
[color=Blue]symbol  [/color][color=Purple]D2 [/color][color=DarkCyan]= [/color][color=Purple]b3                         [/color][color=Green];for all 4 digits[/color]
[color=Blue]symbol  [/color][color=Purple]D1 [/color][color=DarkCyan]= [/color][color=Purple]b4[/color]
[color=Blue]symbol  [/color][color=Purple]D0 [/color][color=DarkCyan]= [/color][color=Purple]b5[/color]


[color=Blue]gosub [/color][color=Black]brightness                        [/color][color=Green];set display brightness[/color]

[color=Blue]for [/color][color=Purple]b1 [/color][color=DarkCyan]= [/color][color=Navy]0 [/color][color=Blue]to [/color][color=Navy]17                        [/color][color=Green];sequence thru all character
  [/color][color=Purple]D3 [/color][color=DarkCyan]= [/color][color=Purple]b1[/color][color=Black]:[/color][color=Purple]D2 [/color][color=DarkCyan]= [/color][color=Purple]b1                       [/color][color=Green];bytes stored in the data 
  [/color][color=Purple]D1 [/color][color=DarkCyan]= [/color][color=Purple]b1[/color][color=Black]:[/color][color=Purple]D0 [/color][color=DarkCyan]= [/color][color=Purple]b1
  [/color][color=Blue]gosub [/color][color=Black]DISPLAY
  [/color][color=Blue]pause [/color][color=Navy]1000[/color]
[color=Blue]next [/color][color=Purple]b1[/color]
[color=Blue]end[/color]

[color=Green];===========================================================================  

;Group of subroutines to read the values from data and output to the display[/color]

[color=Black]DISPLAY:
  [/color][color=Green];Enable sequential movement (from one digit to next)
  [/color][color=Blue]call [/color][color=Black]i2CStart
  [/color][color=Purple]b0 [/color][color=DarkCyan]= [/color][color=Navy]$40
  [/color][color=Blue]call [/color][color=Black]i2CWrByte
  [/color][color=Blue]call [/color][color=Black]i2CStop
  
  [/color][color=Green];Move to first digit
  [/color][color=Blue]call [/color][color=Black]i2CStart 
  [/color][color=Purple]b0 [/color][color=DarkCyan]= [/color][color=Navy]$C0
  [/color][color=Blue]call [/color][color=Black]i2CWrByte

  [/color][color=Green];First value
  [/color][color=Blue]read [/color][color=Purple]D3[/color][color=Black],[/color][color=Purple]b0
  [/color][color=Blue]call [/color][color=Black]i2CWrByte
  
  [/color][color=Green];Second value
  [/color][color=Blue]read [/color][color=Purple]D2[/color][color=Black],[/color][color=Purple]b0
  [/color][color=Blue]if [/color][color=Purple]b1 [/color][color=DarkCyan]= [/color][color=Navy]17 [/color][color=Blue]then                                         
  [/color][color=Purple]b0 [/color][color=DarkCyan]= [/color][color=Purple]b0 [/color][color=DarkCyan]+ [/color][color=Navy]128                         [/color][color=Green];add 128 to turn on colon
  [/color][color=Blue]endif                                             
  call [/color][color=Black]i2CWrByte              

  [/color][color=Green];Third value
  [/color][color=Blue]read [/color][color=Purple]D1[/color][color=Black],[/color][color=Purple]b0
  [/color][color=Blue]call [/color][color=Black]i2CWrByte

  [/color][color=Green];Fourth value
  [/color][color=Blue]read [/color][color=Purple]D0[/color][color=Black],[/color][color=Purple]b0
  [/color][color=Blue]call [/color][color=Black]i2CWrByte
  
  [/color][color=Blue]call [/color][color=Black]i2CStop
  [/color][color=Blue]return[/color]

[color=Black]i2CStart:
  [/color][color=Blue]high clk
  high dio
  low dio
  low clk
  return
  [/color]
[color=Black]i2CStop:
  [/color][color=Blue]low clk
  low dio
  high clk
  high dio
  return[/color]

[color=Green];Send a byte[/color]
[color=Black]i2CWrByte:  [/color][color=Green];outpinC.1 = dio
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit0[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit1[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit2[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit3[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit4[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit5[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit6[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit7[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Blue]return[/color]

[color=Green];Set the brightness ($88 = on, $88 to $8F are the brightness levels)[/color]
[color=Black]brightness:
  [/color][color=Blue]call [/color][color=Black]i2CStart
  [/color][color=Purple]b0 [/color][color=DarkCyan]= [/color][color=Navy]$89
  [/color][color=Blue]call [/color][color=Black]i2CWrByte
  [/color][color=Blue]call [/color][color=Black]i2CStop
  [/color][color=Blue]return
  [/color]
[color=Green];===========================================================================[/color]

Cheers to All

Andrei IRL · Sep 12, 2017

pxgator said:

The TM1637 LED display is widely available, cheap, and an easy way to add a four
digit LED display to a PICAXE project. Borrowing code from the link below I wrote
a version which runs much faster and the code size is reduced. It has been tested from
4 to 32 mhz on M2 parts and also at 64 mhz on X2 parts. The code could be made
to run even faster by converting the subroutines to macros.

Code:

[color=Green];TM1637_test.bas[/color]

[color=Navy]#picaxe [/color][color=Black]08m2[/color]

[color=Green];segment data for TM1637
     ;(  0   1   2   3   4   5   6   7   8   9   A   b   C   d   E   F  dash blank)[/color]
[color=Blue]DATA [/color][color=Navy]0[/color][color=Black],[/color][color=Blue]([/color][color=Navy]$3f[/color][color=Black],[/color][color=Navy]$06[/color][color=Black],[/color][color=Navy]$5b[/color][color=Black],[/color][color=Navy]$4f[/color][color=Black],[/color][color=Navy]$66[/color][color=Black],[/color][color=Navy]$6d[/color][color=Black],[/color][color=Navy]$7d[/color][color=Black],[/color][color=Navy]$07[/color][color=Black],[/color][color=Navy]$7f[/color][color=Black],[/color][color=Navy]$6f[/color][color=Black],[/color][color=Navy]$77[/color][color=Black],[/color][color=Navy]$7c[/color][color=Black],[/color][color=Navy]$39[/color][color=Black],[/color][color=Navy]$5e[/color][color=Black],[/color][color=Navy]$79[/color][color=Black],[/color][color=Navy]$71[/color][color=Black], [/color][color=Navy]$40[/color][color=Black], [/color][color=Navy]$00[/color][color=Blue])[/color]


[color=Green];for TM1637[/color]
[color=Blue]symbol dio [/color][color=DarkCyan]= [/color][color=Blue]C.1                        [/color][color=Green];TM1637 data pin to 08m2 leg 6[/color]
[color=Blue]symbol clk [/color][color=DarkCyan]= [/color][color=Blue]C.2                        [/color][color=Green];TM1637 clock pin to 08m2 leg 5[/color]
[color=Blue]symbol  [/color][color=Purple]D3 [/color][color=DarkCyan]= [/color][color=Purple]b2[/color]
[color=Blue]symbol  [/color][color=Purple]D2 [/color][color=DarkCyan]= [/color][color=Purple]b3                         [/color][color=Green];for all 4 digits[/color]
[color=Blue]symbol  [/color][color=Purple]D1 [/color][color=DarkCyan]= [/color][color=Purple]b4[/color]
[color=Blue]symbol  [/color][color=Purple]D0 [/color][color=DarkCyan]= [/color][color=Purple]b5[/color]


[color=Blue]gosub [/color][color=Black]brightness                        [/color][color=Green];set display brightness[/color]

[color=Blue]for [/color][color=Purple]b1 [/color][color=DarkCyan]= [/color][color=Navy]0 [/color][color=Blue]to [/color][color=Navy]17                        [/color][color=Green];sequence thru all character
  [/color][color=Purple]D3 [/color][color=DarkCyan]= [/color][color=Purple]b1[/color][color=Black]:[/color][color=Purple]D2 [/color][color=DarkCyan]= [/color][color=Purple]b1                       [/color][color=Green];bytes stored in the data 
  [/color][color=Purple]D1 [/color][color=DarkCyan]= [/color][color=Purple]b1[/color][color=Black]:[/color][color=Purple]D0 [/color][color=DarkCyan]= [/color][color=Purple]b1
  [/color][color=Blue]gosub [/color][color=Black]DISPLAY
  [/color][color=Blue]pause [/color][color=Navy]1000[/color]
[color=Blue]next [/color][color=Purple]b1[/color]
[color=Blue]end[/color]

[color=Green];===========================================================================  

;Group of subroutines to read the values from data and output to the display[/color]

[color=Black]DISPLAY:
  [/color][color=Green];Enable sequential movement (from one digit to next)
  [/color][color=Blue]call [/color][color=Black]i2CStart
  [/color][color=Purple]b0 [/color][color=DarkCyan]= [/color][color=Navy]$40
  [/color][color=Blue]call [/color][color=Black]i2CWrByte
  [/color][color=Blue]call [/color][color=Black]i2CStop
  
  [/color][color=Green];Move to first digit
  [/color][color=Blue]call [/color][color=Black]i2CStart 
  [/color][color=Purple]b0 [/color][color=DarkCyan]= [/color][color=Navy]$C0
  [/color][color=Blue]call [/color][color=Black]i2CWrByte

  [/color][color=Green];First value
  [/color][color=Blue]read [/color][color=Purple]D3[/color][color=Black],[/color][color=Purple]b0
  [/color][color=Blue]call [/color][color=Black]i2CWrByte
  
  [/color][color=Green];Second value
  [/color][color=Blue]read [/color][color=Purple]D2[/color][color=Black],[/color][color=Purple]b0
  [/color][color=Blue]if [/color][color=Purple]b1 [/color][color=DarkCyan]= [/color][color=Navy]17 [/color][color=Blue]then                                         
  [/color][color=Purple]b0 [/color][color=DarkCyan]= [/color][color=Purple]b0 [/color][color=DarkCyan]+ [/color][color=Navy]128                         [/color][color=Green];add 128 to turn on colon
  [/color][color=Blue]endif                                             
  call [/color][color=Black]i2CWrByte              

  [/color][color=Green];Third value
  [/color][color=Blue]read [/color][color=Purple]D1[/color][color=Black],[/color][color=Purple]b0
  [/color][color=Blue]call [/color][color=Black]i2CWrByte

  [/color][color=Green];Fourth value
  [/color][color=Blue]read [/color][color=Purple]D0[/color][color=Black],[/color][color=Purple]b0
  [/color][color=Blue]call [/color][color=Black]i2CWrByte
  
  [/color][color=Blue]call [/color][color=Black]i2CStop
  [/color][color=Blue]return[/color]

[color=Black]i2CStart:
  [/color][color=Blue]high clk
  high dio
  low dio
  low clk
  return
  [/color]
[color=Black]i2CStop:
  [/color][color=Blue]low clk
  low dio
  high clk
  high dio
  return[/color]

[color=Green];Send a byte[/color]
[color=Black]i2CWrByte:  [/color][color=Green];outpinC.1 = dio
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit0[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit1[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit2[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit3[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit4[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit5[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit6[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Purple]outpinC.1 [/color][color=DarkCyan]= [/color][color=Purple]bit7[/color][color=Black]:[/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Blue]pulsout clk[/color][color=Black], [/color][color=Navy]1
  [/color][color=Blue]return[/color]

[color=Green];Set the brightness ($88 = on, $88 to $8F are the brightness levels)[/color]
[color=Black]brightness:
  [/color][color=Blue]call [/color][color=Black]i2CStart
  [/color][color=Purple]b0 [/color][color=DarkCyan]= [/color][color=Navy]$89
  [/color][color=Blue]call [/color][color=Black]i2CWrByte
  [/color][color=Blue]call [/color][color=Black]i2CStop
  [/color][color=Blue]return
  [/color]
[color=Green];===========================================================================[/color]

Cheers to All

Thanks very much for the code.

I have ordered a few of these screens and planning on trying to implement one into my project.

Would you be able to put up a schematic diagram in terms of pin conecction from screen to PICAXE please?

I am using PICAXE14M2 if that makes a difference.

Thanks very much.

Andrei.

hippy · Sep 12, 2017

It seems to be an I2C connection, so just two signals plus power ...

Code:

symbol dio = C.1 ;TM1637 data pin to 08m2 leg 6
symbol clk = C.2 ;TM1637 clock pin to 08m2 leg 5

Not studied the TM1367 datasheet but I would have thought the bit-banged I2C software could be replaced by HI2C commands to simplify things, improve speeds and reduce memory. That would swap the two pins around; CLK on C.1, SDA on C.2.

pxgator · Sep 23, 2017

Andrei IRL said:
Thanks very much for the code.

I have ordered a few of these screens and planning on trying to implement one into my project.

Would you be able to put up a schematic diagram in terms of pin conecction from screen to PICAXE please?

I am using PICAXE14M2 if that makes a difference.

Thanks very much.

Andrei.

The code is using bit banged I2C so any pins that can be outputs could be used.
I've never been able to get the correct data on this part in order to use real I2C.
The bit banged I2C is quite quick with my code.

Cheers to All

P.S. Even the available Arduino code examples for
this part uses bit banged I2C.

PhilHornby · Sep 24, 2017

Risk of "Magic Smoke"

pxgator said:
The code is using bit banged I2C so any pins that can be outputs could be used.

I've seen a few example of using bit-banged I2C in the forum, but none seem to have addressed this issue :-

Code:

From the PIC datasheet:

Both the SCL and SDA connections are bidirectional [B]open-drain[/B] lines, each requiring pull-up resistors for the supply voltage

Presumably there is no way to manually configure an Output Pin to be open-drain, so how are potential clashes to be avoided (i.e. PIC o/p @ logic 1, other bus member at logic 0).

Would a simple resistor (or diode?) do the job, or is an external transistor necessary?

hippy · Sep 24, 2017

I am sure that some of my example code has dealt with the open-drain issue; that is achieved by only using INPUT and LOW commands, never setting the pin high.

There used to be issues with earlier PICAXE devices because they had fixed input and output pins, but with the modern M2 and X2 devices that is not a problem.

I would recommend using the same pins for bit-banging as the PICAXE uses for hardware does because it's then easy to switch between the two, and it also helps when developing code knowing that the other mechanism works. That applies to SPI and UART connections as much as to I2C.

This is example code I have for an old 08M which uses INPUT and LOW only -

Code:

; *****************************************************************************
; *                                                                           *
; *     I2C Test Program for the PICAXE-08M                     I2C6.BAS      *
; *                                     ^^^                                   *
; *****************************************************************************
; *                                                                           *
; *     This is an version of I2C3.BAS specifically designed to run on the    *
; *     PICAXE-08M using its bi-directional port abilities.                   *
; *                                                                           *
; *     The core I2C routines use just 140 bytes of code.                     *
; *                                                                           *
; *****************************************************************************

;                              --.---.-- +V
;                               .|. .|.
;                               | | | | 2 x 4K7
;                               |_| |_|
;        PICAXE-08M              |   |           I2C Eeprom / Ram
;       .----------.             |   |             .----------.
;       |       X1 |-------------^---|-------------| SDA   A2 |---.
;       |          |                 |             |       A1 |---{
;       |       X4 |-----------------^-------------| SCL   A0 |---{
;       `----------'                               |       WP |---{
;                                                  `----------'  _|_ 0V

; *****************************************************************************
; *                                                                           *
; *     Define the I2C device being used                                      *
; *                                                                           *
; *****************************************************************************

                                                ; 24LC256, Word Addressed

        Symbol  I2C_ADDRESS     = %10100000     ; $A0

; *****************************************************************************
; *                                                                           *
; *     Variables                                                             *
; *                                                                           *
; *****************************************************************************

        Symbol  tstAdr          = b0
        Symbol  tstVal          = b1

        Symbol  i2cAdr          = w1    ' b3:b2
        Symbol  i2cAdrLsb       = b2
        Symbol  i2cAdrMsb       = b3

        Symbol  i2cVal          = b4

        Symbol  i2cDataByte     = b5
        Symbol  i2cAckBit       = b6
        Symbol  i2cBitCount     = b7

; *****************************************************************************
; *                                                                           *
; *     Bit-Banged I/O definitions                                            *
; *                                                                           *
; *****************************************************************************

        Symbol  SDA             = 1
        Symbol  SCL             = 4

        Symbol  SDA_PIN         = pin1
        Symbol  SCL_PIN         = pin4

; *****************************************************************************
; *                                                                           *
; *     Main Program Code                                                     *
; *                                                                           *
; *****************************************************************************

        ; Wait for Terminal Window Pop-Up

        Pause 1000

        ; Initialise the I2C comms

        Gosub InitI2cDevice

        ; Test I2C

        For i2cAdr = $00 To $3F
          i2cVal = i2cAdr+3
          Gosub WriteI2cData
          Gosub ReadI2cData
          i2cVal = i2cVal-3
          If i2cVal <> i2cAdr Then
            SerTxd( "Er" )
          End If
        Next

        SerTxd( "Ok" )

        End

; *****************************************************************************
; *                                                                           *
; *     High-Level I2C Interface Routines                                     *
; *                                                                           *
; *****************************************************************************

WriteI2cData:

        Gosub I2cSendHeader

        i2cDataByte = i2cVal
        Gosub I2cSendByte

        Gosub InitI2cDevice

        Pause 20                        ; 20mS to allow write

        Return

ReadI2cData:

        Gosub I2cSendHeader

        Gosub I2cStart

        i2cDataByte = I2C_ADDRESS | $01
        Gosub I2cSendByte

        Input SDA                       ; SDA = 1 / Tri-State SDA
        For i2cBitCount = 0 To 7
          Gosub I2cStrobeScl
          i2cVal= i2cVal * 2 | i2cAckBit
        Next

InitI2cDevice:

        Low SCL                         ; SCL = 0
        Low SDA                         ; SDA = 0
        Input SCL                       ; SCL = 1
        Input SDA                       ; SDA = 1
        Return

; *****************************************************************************
; *                                                                           *
; *     Low-Level I2C Interface                                               *
; *                                                                           *
; *****************************************************************************

I2cSendHeader:

        Gosub I2cStart

        i2cDataByte = I2C_ADDRESS & $FE
        Gosub I2cSendByte

        i2cDataByte = i2cAdrMsb
        Gosub I2cSendByte

        i2cDataByte = i2cAdrLsb

I2cSendByte:

        For i2cBitCount = 0 TO 7
          If i2cDataByte < $80 Then
            Low SDA                     ; SDA = 0
          Else
            Input SDA                   ; SDA = 1
          End If
          Gosub I2cStrobeScl
          i2cDataByte = i2cDataByte * 2
        Next
        Input SDA                       ; SDA = 1 / Tri-State SDA
        Gosub I2cStrobeScl
; ---   if i2cAckBit = 1 Then
; ---     SerTxd( "ACK FAILED",CR,LF )
; ---   end if
        Return

I2cStart:

        Input SDA                       ; SDA = 1
        Input SCL                       ; SCL = 1
        Low SDA                         ; SDA = 0
        Low SCL                         ; SCL = 0
        Return

I2cStrobeScl:

        Input SCL                       ; SCL = 1
        Do
        Loop Until SCL_PIN = 1
        i2cAckBit = SDA_PIN
        Low SCL                         ; SCL = 0
        Return

; *****************************************************************************
; *                                                                           *
; *     End of program                                                        *
; *                                                                           *
; *****************************************************************************

PhilHornby · Sep 24, 2017

hippy said:
I am sure that some of my example code has dealt with the open-drain issue; that is achieved by only using INPUT and LOW commands, never setting the pin high.

Very clever - I'd not thought of that.

pxgator · Sep 25, 2017

I have used the code posted above with 08M2's, 14M2's, and 20X2's on many TM1637 LED
display projects. All have and still are working perfectly. Maybe the TM1637 is not truly
an I2C device??

Cheers to All

hippy · Sep 25, 2017

pxgator said:
Maybe the TM1637 is not truly an I2C device??

It seemed to be from the datasheets I looked at and the bit-banged code earlier. Talking of which -

Code:

  outpinC.1 = bit7:pulsout clk, 1
  pulsout clk, 1
  return

That's a bit iffy as PhilHornby noted above. It is clocking in an ACK from the I2C device which, if bit7 just happens to have set C.1 high, will be trying to pull that high to 0V. Admittedly only for a short period of time.

pxgator · Sep 25, 2017

Thanks for the info hippy but like I mentioned above the code and
setup that I use with PICAXE chips and the TM1637 have worked
trouble free for a long time. I've never experienced any errors.

Cheers to All

hippy · Feb 21, 2018

hippy said:
pxgator said:

Maybe the TM1637 is not truly an I2C device??

Click to expand...

It seemed to be from the datasheets I looked at and the bit-banged code earlier.

Having had cause to look at the datasheet more recently it is fair to say it uses an I2C-style protocol but is not what one would call a traditional I2C device. The device doesn't have a Device ID and the command and data bits are sent lsb first rather than msb first as is the case with usual I2C.

Because of the TM1637 peculiarities it would seem difficult to control it using I2C commands which would be used to control other I2C devices and bit-banging would appear to be the most appropriate way to do that.

premelec · Dec 7, 2018

FWIW I started to strip color html from #1 code post here... ;-0
Not quite there yet - I'll be back...

Code:

;TM1637_test.bas

#picaxe 08m2

;segment data for TM1637
;(  0   1   2   3   4   5   6   7   8   9   A   b   C   d   E   F  dash blank)
DATA 0,($3f,$06,$5b,$4f,$66,$6d,$7d,$07,$7f,$6f,$77,$7c,$39,$5e,$79,$71, $40, $00)


;for TM1637
symbol dio = C.1                        ;TM1637 data pin to 08m2 leg 6
symbol clk = C.2                        ;TM1637 clock pin to 08m2 leg 5
symbol  D3 = b2
symbol  D2 = b3                         ;for all 4 digits
symbol  D1 = b4
symbol  D0 = b5


gosub brightness                        ;set display brightness

for b1 = 0 to 17                        ;sequence thru all character
  D3 = b1:D2 = b1                       ;bytes stored in the data
  D1 = b1:D0 = b1
  gosub DISPLAY
  pause 1000
next b1
end

;===========================================================================

;Group of subroutines to read the values from data and output to the display

DISPLAY:
  ;Enable sequential movement (from one digit to next)
  call i2CStart
  b0 = $40
  call i2CWrByte
  call i2CStop

  ;Move to first digit
  call i2CStart
  b0 = $C0
  call i2CWrByte

  ;First value
  read D3,b0
  call i2CWrByte

  ;Second value
  read D2,b0
  if b1 = 17 then                                      
  b0 = b0 + 128                         ;add 128 to turn on colon
  endif                                          
  call i2CWrByte           

  ;Third value
  read D1,b0
  call i2CWrByte

  ;Fourth value
  read D0,b0
  call i2CWrByte

  call i2CStop
  return

i2CStart:
  high clk
  high dio
  low dio
  low clk
  return

i2CStop:
  low clk
  low dio
  high clk
  high dio
  return

;Send a byte
i2CWrByte:  ;outpinC.1 = dio
  outpinC.1 = bit0:pulsout clk, 1
  outpinC.1 = bit1:pulsout clk, 1
  outpinC.1 = bit2:pulsout clk, 1
  outpinC.1 = bit3:pulsout clk, 1
  outpinC.1 = bit4:pulsout clk, 1
  outpinC.1 = bit5:pulsout clk, 1
  outpinC.1 = bit6:pulsout clk, 1
  outpinC.1 = bit7:pulsout clk, 1
  pulsout clk, 1
  return

;Set the brightness ($88 = on, $88 to $8F are the brightness levels)
brightness:
  call i2CStart
  b0 = $89
  call i2CWrByte
  call i2CStop
  return

;===========================================================================

;Cheers to All
;Last edited: Sep 23, 2017

hippy · Dec 7, 2018

premelec said:
FWIW I started to strip color html from #1 code post here... ;-0

If you replace the opening [code] tag in post#1 with [code="rich"] That should do everything for you.

Buzby · Dec 7, 2018

Rich (BB code):

;TM1637_test.bas

#picaxe 08m2

;segment data for TM1637
     ;(  0   1   2   3   4   5   6   7   8   9   A   b   C   d   E   F  dash blank)
DATA 0,($3f,$06,$5b,$4f,$66,$6d,$7d,$07,$7f,$6f,$77,$7c,$39,$5e,$79,$71, $40, $00)


;for TM1637
symbol dio = C.1                        ;TM1637 data pin to 08m2 leg 6
symbol clk = C.2                        ;TM1637 clock pin to 08m2 leg 5
symbol  D3 = b2
symbol  D2 = b3                         ;for all 4 digits
symbol  D1 = b4
symbol  D0 = b5


gosub brightness                        ;set display brightness

for b1 = 0 to 17                        ;sequence thru all character
  D3 = b1:D2 = b1                       ;bytes stored in the data 
  D1 = b1:D0 = b1
  gosub DISPLAY
  pause 1000
next b1
end

;===========================================================================  

;Group of subroutines to read the values from data and output to the display

DISPLAY:
  ;Enable sequential movement (from one digit to next)
  call i2CStart
  b0 = $40
  call i2CWrByte
  call i2CStop
  
  ;Move to first digit
  call i2CStart 
  b0 = $C0
  call i2CWrByte

  ;First value
  read D3,b0
  call i2CWrByte
  
  ;Second value
  read D2,b0
  if b1 = 17 then                                         
  b0 = b0 + 128                         ;add 128 to turn on colon
  endif                                             
  call i2CWrByte              

  ;Third value
  read D1,b0
  call i2CWrByte

  ;Fourth value
  read D0,b0
  call i2CWrByte
  
  call i2CStop
  return

i2CStart:
  high clk
  high dio
  low dio
  low clk
  return
  
i2CStop:
  low clk
  low dio
  high clk
  high dio
  return

;Send a byte
i2CWrByte:  ;outpinC.1 = dio
  outpinC.1 = bit0:pulsout clk, 1
  outpinC.1 = bit1:pulsout clk, 1
  outpinC.1 = bit2:pulsout clk, 1
  outpinC.1 = bit3:pulsout clk, 1
  outpinC.1 = bit4:pulsout clk, 1
  outpinC.1 = bit5:pulsout clk, 1
  outpinC.1 = bit6:pulsout clk, 1
  outpinC.1 = bit7:pulsout clk, 1
  pulsout clk, 1
  return

;Set the brightness ($88 = on, $88 to $8F are the brightness levels)
brightness:
  call i2CStart
  b0 = $89
  call i2CWrByte
  call i2CStop
  return
  
;===========================================================================

Easy 4 digit LED display

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