Vsm i2c simulation of mcp23017

[scamanderriver]

Hi, can someone put me out of my misery please
I've been trying to learn how to use the MCP23017 expander via I2c protocol
but no matter what i do I cannot get it to simulate on VSM
My knowledge of I2C protocol is basic so I've been using examples posted on the forum as a learning aid, but without success.
So the question needs to be asked,
does VSM actually simulate I2C with the MP23017 ??

thanks

 

[nick12ab]

I don't have VSM, but could you post your code so that it can be confirmed that you are using a hi2csetup command and with the correct slave address.

 

[scamanderriver]

I don't have VSM, but could you post your code so that it can be confirmed that you are using a hi2csetup command and with the correct slave address.

Sure happy to,

I am not sure of what am doing, so to learn I have tried many versions including writei2c commands as well, frustratingly without success.
I am using the new version of VSM

I have mainly been using hi2c commands instead of i2c commands as recommended in manual2
Unfortunately the i2c tutorial focuses on these older commands so is not really a help.

;Code for BASIC test of MCP23017, based from code posted by westaust55
;USING 40X2 ON VSM

SYMBOL mcp23017 = %01000000 ; $0100 A2, A1, A0, R/W all connected to 0V
SYMBOL IODIRA = $00 ; Port A IO Direction register DEFAULT = I/P
SYMBOL IODIRB = $01 ; Port B IO Direction register DEFAULT = I/P
SYMBOL IOCON = $0A ; IO Expander config register - address $0B accesses the same register
SYMBOL GPIOA = $12 ; Port A General purpose register
SYMBOL GPIOB = $13 ; Port B General Purpose register

HI2CSETUP i2cmaster, mcp23017, i2cFAST_8, i2cbyte
; I have tried i2cfast, i2cslow_8,
PAUSE 100

HI2COUT IODIRA, ($FF) ;set all port A pins as inputs (1)
HI2COUT IODIRB, ($00) ;set all port B pins as outputs (0)

PAUSE 100

HI2COUT $12, (%11111111) ; all ON
PAUSE 300
HI2COUT $12, (%00000000) ; all OFF
PAUSE 300

HI2COUT $13, (%11111111) ; all ON
PAUSE 300
HI2COUT $13, (%00000000) ; all OFF
PAUSE 300


Main:
DO
b3 = 1
DO ; LED dot pattern to move left
HI2COUT GPIOB, (b3)
b3 = b3 << 1 ; shift left 1 bit
PAUSE 500
LOOP UNTIL b3 = 0

b3 = 64
DO ; LED dot pattern to move right
HI2COUT GPIOB, (b3)
b3 = b3 >> 1 ; shift right 1 bit
PAUSE 500
LOOP UNTIL b3 = 1

LOOP

Thanks for your help

 

[hippy]

So the question needs to be asked,
does VSM actually simulate I2C with the MP23017 ??

Your code seemed to work for me without any changes when I tried it, so it seems -

1) You haven't wired the MCP23017 correctly; ensure /RESET goes to +V, A2/A1/A0 to 0V, SCL/SDA go to the correct 40X2 pins, aren't crossed-over and have pull-ups..

2) My VSM setup is different to your, which is possible as X2's are Beta releases.

Perhaps post your .DSN file so those with PICAXE VSM can check and test that.

 

[scamanderriver]

Your code seemed to work for me without any changes when I tried it, so it seems -
1) You haven't wired the MCP23017 correctly; ensure /RESET goes to +V, A2/A1/A0 to 0V, SCL/SDA go to the correct 40X2 pins, aren't crossed-over and have pull-ups..

THANK YOU VERY VERY MUCH
You were right !!

I hadn't connected the RESET to +ve

Now it works fine.
I really appreciate your help,
if my hair was long i probably would have pulled it out by now.
Cheers