I'm still working on it...I'm studying the SHT-11 docs & the BS2 code, which works, and now I can't figure out why. According to the doc, the SHT-11 defaults to a 12-bit measurement, and the BS2 code appears to assume 8-bit readings. I still haven't been able to get the Picaxe to get a coherent reading.
Here's the current version of the program, but I expect to be working on this till bedtime. (9:00 or so) Any help is vastly appreciated.
' Simple SHT-11 interface, BS2 to Picaxe-08M
symbol dat = pin1 ' bi-directional data
symbol sin = input1
symbol Clk = pin2
symbol MSBvalue = 128 ' MSBvalue (=128 for 8 bits, 512 for 10 bits, 2048 for 12 bits)
symbol ack = bit0
symbol timeout = bit1
symbol sorh = w2
symbol counter = b7 ' variable used during loop
symbol mask = w4 ' bit masking variable
symbol var_in = w5 ' data variable used durig shiftin
symbol var_out = w6 ' data variable used during shiftout
' Initialization
Initialize:
pause 1000
GOSUB SHT_Connection_Reset ' reset device connection
PAUSE 1000 ' let DEBUG window open
Main:
GOSUB SHT_Measure_Humidity
sertxd("Raw: ",#sorh, 13, 10)
PAUSE 2000
if timeout = 1 then goto ender ' minimum delay between readings
GOTO Main
ender:
end
' ------------------------------------------------------------------------------
' Subroutines
' ------------------------------------------------------------------------------
' connection reset: 9 clock cyles with ShtData high, then start sequence
SHT_Connection_Reset:
input 1
ack = dat
sertxd("rst",#ack,13,10)
for counter = 1 to 9
pulsout 2,1
pause 10
next counter
SHT_Start:
INPUT 1 ' let pull-up take line high
LOW 2
HIGH 2
LOW 1
LOW 2
high 2
INPUT 1
LOW 2
RETURN
' measure humidity
SHT_Measure_Humidity:
'sertxd("H:", 13, 10)
GOSUB SHT_Start ' alert device
var_out = %00000101 ' humidity command
GOSUB SHT_Write_Byte ' send command
GOSUB SHT_Wait ' wait until measurement done
Ack = 0 ' another read follows
GOSUB SHT_Read_Byte
b4 = var_in ' get MSB
ack = 1 ' last read
GOSUB SHT_Read_Byte ' get LSB
b5 = var_in
RETURN
SHT_Write_Byte:
gosub shiftout_MSB_First ' send byte
gosub getack
RETURN
SHT_Read_Byte:
sertxd("R",13,10)
gosub shiftin_MSB_Pre
gosub sendack
INPUT 1 ' release data line
RETURN
SHT_Wait:
ack = 0
timeout = 0
INPUT 1 ' data line is input
FOR counter = 1 TO 250 ' give ~1/4 second to finish
sertxd (#counter) ack = dat ' scan data line
IF ack = 0 THEN SHT_Wait_Done ' if low, we're done
PAUSE 1
NEXT counter
if counter > 249 then
timeout = 1
sertxd("X"
' Timeout indicator
endif
SHT_Wait_Done:
sertxd("O",13,10) ' Signal has been received
RETURN
shiftout_MSB_first:
for counter = 1 to 8
mask = var_out & MSBValue
low 1
if mask = 0 then skipMSB
input 1 ' data high
skipMSB:
pulsout 2,1 ' pulse clock for 10us
var_out = var_out * 2 ' shift variable left for MSB
next counter
return
#rem
shiftout_LSBFirst:
for counter = 1 to 9 ' number of bits
mask = var_out & 1 ' mask LSB
low 1 ' data low
if mask = 0 then skipLS
input 1 ' data high
skipLS:
pulsout 2,1 ' pulse clock for 10us
var_out = var_out / 2 ' shift variable right for LSB
next counter
return
shiftin_LSB_pre:
for counter = 1 to 8
mask = var_out & 1
low 1
if mask = 0 then skipLSB
input 1
skipLSB: pulsout 2,1
var_out = var_out / 2
next counter
RETURN
#endrem
shiftin_MSB_Pre:
let var_in = 0
for counter = 1 to 8 ' number of bits
var_in = var_in * 2 ' shift left as MSB first
if dat = 0 then skipMSBPre
var_in = var_in + 1 ' set LSB if serdata = 1
skipMSBPre:
pulsout 2,1 ' pulse clock to get next data bit
next counter
return
getack: 'Gets ack bit from SHT-11
input 1
do
if dat=0 then exit
loop
pulsout 2,1
return
sendack:
'Sends ack bit to SHT-11
if ack = 1 then
input 1
else
low 1
endif
pulsout 2,1
return
Here's the current version of the program, but I expect to be working on this till bedtime. (9:00 or so) Any help is vastly appreciated.
' Simple SHT-11 interface, BS2 to Picaxe-08M
symbol dat = pin1 ' bi-directional data
symbol sin = input1
symbol Clk = pin2
symbol MSBvalue = 128 ' MSBvalue (=128 for 8 bits, 512 for 10 bits, 2048 for 12 bits)
symbol ack = bit0
symbol timeout = bit1
symbol sorh = w2
symbol counter = b7 ' variable used during loop
symbol mask = w4 ' bit masking variable
symbol var_in = w5 ' data variable used durig shiftin
symbol var_out = w6 ' data variable used during shiftout
' Initialization
Initialize:
pause 1000
GOSUB SHT_Connection_Reset ' reset device connection
PAUSE 1000 ' let DEBUG window open
Main:
GOSUB SHT_Measure_Humidity
sertxd("Raw: ",#sorh, 13, 10)
PAUSE 2000
if timeout = 1 then goto ender ' minimum delay between readings
GOTO Main
ender:
end
' ------------------------------------------------------------------------------
' Subroutines
' ------------------------------------------------------------------------------
' connection reset: 9 clock cyles with ShtData high, then start sequence
SHT_Connection_Reset:
input 1
ack = dat
sertxd("rst",#ack,13,10)
for counter = 1 to 9
pulsout 2,1
pause 10
next counter
SHT_Start:
INPUT 1 ' let pull-up take line high
LOW 2
HIGH 2
LOW 1
LOW 2
high 2
INPUT 1
LOW 2
RETURN
' measure humidity
SHT_Measure_Humidity:
'sertxd("H:", 13, 10)
GOSUB SHT_Start ' alert device
var_out = %00000101 ' humidity command
GOSUB SHT_Write_Byte ' send command
GOSUB SHT_Wait ' wait until measurement done
Ack = 0 ' another read follows
GOSUB SHT_Read_Byte
b4 = var_in ' get MSB
ack = 1 ' last read
GOSUB SHT_Read_Byte ' get LSB
b5 = var_in
RETURN
SHT_Write_Byte:
gosub shiftout_MSB_First ' send byte
gosub getack
RETURN
SHT_Read_Byte:
sertxd("R",13,10)
gosub shiftin_MSB_Pre
gosub sendack
INPUT 1 ' release data line
RETURN
SHT_Wait:
ack = 0
timeout = 0
INPUT 1 ' data line is input
FOR counter = 1 TO 250 ' give ~1/4 second to finish
sertxd (#counter) ack = dat ' scan data line
IF ack = 0 THEN SHT_Wait_Done ' if low, we're done
PAUSE 1
NEXT counter
if counter > 249 then
timeout = 1
sertxd("X"
' Timeout indicatorendif
SHT_Wait_Done:
sertxd("O",13,10) ' Signal has been received
RETURN
shiftout_MSB_first:
for counter = 1 to 8
mask = var_out & MSBValue
low 1
if mask = 0 then skipMSB
input 1 ' data high
skipMSB:
pulsout 2,1 ' pulse clock for 10us
var_out = var_out * 2 ' shift variable left for MSB
next counter
return
#rem
shiftout_LSBFirst:
for counter = 1 to 9 ' number of bits
mask = var_out & 1 ' mask LSB
low 1 ' data low
if mask = 0 then skipLS
input 1 ' data high
skipLS:
pulsout 2,1 ' pulse clock for 10us
var_out = var_out / 2 ' shift variable right for LSB
next counter
return
shiftin_LSB_pre:
for counter = 1 to 8
mask = var_out & 1
low 1
if mask = 0 then skipLSB
input 1
skipLSB: pulsout 2,1
var_out = var_out / 2
next counter
RETURN
#endrem
shiftin_MSB_Pre:
let var_in = 0
for counter = 1 to 8 ' number of bits
var_in = var_in * 2 ' shift left as MSB first
if dat = 0 then skipMSBPre
var_in = var_in + 1 ' set LSB if serdata = 1
skipMSBPre:
pulsout 2,1 ' pulse clock to get next data bit
next counter
return
getack: 'Gets ack bit from SHT-11
input 1
do
if dat=0 then exit
loop
pulsout 2,1
return
sendack:
'Sends ack bit to SHT-11
if ack = 1 then
input 1
else
low 1
endif
pulsout 2,1
return