Connecting the TPA81 to the BS2, BS2e, BS2sx, BS2p
Introduction
The TPA81 module uses the I2C bus for communication. This example shows how to connect
the TPA81 module to
the BS2 family. The SDA (data) and SCL (clock) lines are connected to
pins P8 and P9 on the Stamp. These are the pins used by the BS2p for the I2CIN and
I2COUT commands. The internal 5v regulator is not suitable for powering much external
circuitry. I therefore recommend you use a separate 5v regulator.
Circuit Schematic for connecting a TPA81 Module to the Basic Stamp BS2p
The schematic above shows 4k7 pull-up resistors on the SCL and SDA lines to
Vdd, as recommended by Parallax.
For greater noise immunity, I recommend pulling up to the TPA81's 5v supply
instead (so as not to place any more load on the BS2) and using 1k8 resistors.
Displaying temperature readings in a PC Debug window - BS2p Version
The following sample code will display the firmware revision, ambient
temperature and the 8 pixel temperatures in a Debug window on the PC
.
The sample code below can be downloaded here.
'{$STAMP BS2p}
'***********************************************************
'** **
'** I2C Routines for the Basic Stamp BS2p **
'** with the TPA81 Thermal sensor module **
'** **
'** Copyright 2005 - Devantech Ltd **
'** Commercial use of this software is prohibited **
'** Private and educational use only is permitted **
'** **
'** Written by Gerald Coe - February 2005 **
'** **
'***********************************************************
' Connect P8 (pin13) of the BS2p to the TPA81 SDA ' Connect P9 (pin14) of the BS2p to the TPA81 SCL ' Use 4k7 pull-up resistors from SCL and SDA to 5v supply SDA CON 8 ' SDA on pin13, SCL on pin14 Ver VAR Byte Ambient VAR Byte Pix1 VAR Byte Pix2 VAR Byte Pix3 VAR Byte Pix4 VAR Byte Pix5 VAR Byte Pix6 VAR Byte Pix7 VAR Byte Pix8 VAR Byte Loop: I2CIN SDA, $d1, 0, [Ver, Ambient, Pix1, Pix2, Pix3, Pix4, Pix5, Pix6, Pix7, Pix8 ] DEBUG 2,0,1, "BS2p - TPA81 Demonstration " DEBUG 2,0,2, "Firmware Version ", DEC Ver, " " DEBUG 2,0,3, "Ambient ", DEC Ambient, " " DEBUG 2,0,4, "Pix1 Pix2 Pix3 Pix4 Pix5 Pix6 Pix7 Pix8" DEBUG 2,0,5, DEC3 Pix1, " ", DEC3 Pix2, " ", DEC3 Pix3, " ", DEC3 Pix4, " ", DEC3 Pix5, " ", DEC3 Pix6, " ", DEC3 Pix7, " ", DEC3 Pix8 GOTO Loop |
Displaying temperature readings in a PC Debug window - BS2, BS2e,
BS2sx Versions
The following sample code will display the firmware revision, ambient
temperature and the 8 pixel temperatures in a Debug window on the PC
.
The sample code below can be downloaded here.
'{$STAMP BS2}
'***********************************************************
'** **
'** I2C Routines for the Basic Stamp BS2/BS2e/BS2sx **
'** with the TPA81 Thermal sensor module **
'** **
'** Copyright 2006 - Devantech Ltd **
'** Commercial use of this software is prohibited **
'** Private and educational use only is permitted **
'** **
'** Written by Gerald Coe - March 2006 **
'** **
'***********************************************************
' Connect P8 (pin13) of the BS2 to the TPA81 SDA ' Connect P9 (pin14) of the BS2 to the TPA81 SCL ' Use 4k7 pull-up resistors from SCL and SDA to 5v supply SDA CON 8 ' I2C data SCL CON 9 ' I2C clock SDAin VAR IN8 SDAout VAR OUT8 SDAdir VAR DIR8 Ver VAR Byte Ambient VAR Byte Pix1 VAR Byte Pix2 VAR Byte Pix3 VAR Byte Pix4 VAR Byte Pix5 VAR Byte Pix6 VAR Byte Pix7 VAR Byte Pix8 VAR Byte I2cBuf VAR Byte ' I2c read/write buffer I2cAddr VAR Byte ' Address of I2C device I2cReg VAR Byte ' Register number within I2C device I2cData VAR Word ' Data to read/write I2cAck VAR Bit ' Acknowledge bit DEBUG 2,0,1, "BS2/BS2e/BS2sx - TPA81 Demonstration " DEBUG 2,0,2, "Firmware Version " DEBUG 2,0,3, "Ambient " DEBUG 2,0,4, "Pix1 Pix2 Pix3 Pix4 Pix5 Pix6 Pix7 Pix8" I2cAddr = $D0 I2cReg = 0 MainLoop: GOSUB I2cTPA81Read ' read data from TPA81 DEBUG 2,17,2, DEC Ver, " " DEBUG 2,8,3, DEC Ambient, " " DEBUG 2,0,5, DEC3 Pix1, " ", DEC3 Pix2, " ", DEC3 Pix3, " ", DEC3 Pix4, " ", DEC3 Pix5, " ", DEC3 Pix6, " ", DEC3 Pix7, " ", DEC3 Pix8 GOTO MainLoop '-------------------------------------------------------------------------------------------- ' I2C subroutines follow '-------------------------------------------------------------------------------------------- I2cTPA81Read: I2cAck = 1 ' send Ack GOSUB I2cStart I2cBuf = I2cAddr GOSUB I2cOutByte ' send device address I2cBuf = I2cReg GOSUB I2cOutByte ' send register number GOSUB I2cStart ' repeated start I2cBuf = I2cAddr | 1 I2cAck = 1 ' send Ack GOSUB I2cOutByte ' send device address (with read set) GOSUB I2cInByte Ver = I2cBuf ' read the data GOSUB I2cInByte Ambient = I2cBuf GOSUB I2cInByte Pix1 = I2cBuf GOSUB I2cInByte Pix2 = I2cBuf GOSUB I2cInByte Pix3 = I2cBuf GOSUB I2cInByte Pix4 = I2cBuf GOSUB I2cInByte Pix5 = I2cBuf GOSUB I2cInByte Pix6 = I2cBuf GOSUB I2cInByte Pix7 = I2cBuf I2cAck = 0 ' send Nak GOSUB I2cInByte Pix8 = I2cBuf GOSUB I2cStop RETURN I2cByteWrite: ' writes I2cData.lowbyte to I2cReg at I2cAddr GOSUB I2cStart I2cBuf = I2cAddr GOSUB I2cOutByte ' send device address I2cBuf = I2cReg GOSUB I2cOutByte ' send register number I2cBuf = I2cData.LOWBYTE GOSUB I2cOutByte ' send the data GOSUB I2cStop RETURN I2cWordWrite: ' writes I2cData to I2cReg at I2cAddr GOSUB I2cStart I2cBuf = I2cAddr GOSUB I2cOutByte ' send device address I2cBuf = I2cReg GOSUB I2cOutByte ' send register number I2cBuf = I2cData.HIGHBYTE GOSUB I2cOutByte ' send the data - high byte I2cBuf = I2cData.LOWBYTE GOSUB I2cOutByte ' send the data - low byte GOSUB I2cStop RETURN I2CByteRead: GOSUB I2cStart I2cBuf = I2cAddr GOSUB I2cOutByte ' send device address I2cBuf = I2cReg GOSUB I2cOutByte ' send register number GOSUB I2cStart ' repeated start I2cBuf = I2cAddr | 1 GOSUB I2cOutByte ' send device address (with read set) I2cAck = 0 ' send Nak GOSUB I2cInByte I2cData.LOWBYTE = I2cBuf ' read the data I2cData.HIGHBYTE = 0 GOSUB I2cStop RETURN I2CWordRead: GOSUB I2cStart I2cBuf = I2cAddr GOSUB I2cOutByte ' send device address I2cBuf = I2cReg GOSUB I2cOutByte ' send register number GOSUB I2cStart ' repeated start I2cBuf = I2cAddr | 1 I2cAck = 1 ' send Ack GOSUB I2cOutByte ' send device address (with read set) GOSUB I2cInByte I2cData.HIGHBYTE = I2cBuf ' read the data I2cAck = 0 ' send Nak GOSUB I2cInByte I2cData.LOWBYTE = I2cBuf GOSUB I2cStop RETURN I2cOutByte: SHIFTOUT SDA, SCL, MSBFIRST, [I2cBuf] INPUT SDA HIGH SCL ' clock in the ack' bit LOW SCL RETURN I2cInByte: SHIFTIN SDA, SCL, MSBPRE, [I2cBuf] SDAout = 0 SDAdir = I2cAck HIGH SCL ' clock out the ack' bit LOW SCL INPUT SDA RETURN I2cStart ' I2C start bit sequence HIGH SDA HIGH SCL LOW SDA LOW SCL RETURN I2cStop: ' I2C stop bit sequence LOW SDA HIGH SCL HIGH SDA RETURN |