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Hello, I've been studying the code on peter anderson's website regarding the TI TLC2543 ADC, and have a few questions for those of you who are experienced with playing around with it! Here is the code verbatim from his website: Program TLC2543_1.Bas ' ' Illustrates how to perform a single measurment on a specific ' channel. ' ' Performs unipolar measurments on each of the 11 channels, displaying ' the results on the terminal (Com 1) and then powers down A/D. ' ' Note that the format of the command byte is; ' ' C C C C L1 L0 LSB BIPOLAR ' ' where C is the channel (0 - 10). ' L1 and L0 = 11 binary indicates 16-bit format. ' LSB is zero for most sig byte first. ' BIPOLAR is 0 for unipolar measurement. ' ' The command byte is sent followed by a dummy byte so as to send 16 bits. ' ' This is followed by a 16-bit read of the result where the 12-bit result ' is in the high 12-bits. This is shifted right (\16) such that the result ' is in the lower 12 bits. ' ' Note that in TLC2543_2, the process is speeded up a bit by sending the ' command for the next measurement while the previous result is being ' fetched. ' ' BX24 TLC2543 ' ' MISO <---------------- D_Out (Term 16) ' MOSI ----------------> D_in (Term 17) ' SCLK ----------------> CLK (Term 18) ' ' /CS (term 13) -------> /CS (Term 15) ' ' See http://www.ti.com for a data sheet. ' ' copyright, Peter H. Anderson, Baltimore, MD, Sept, '00 Const CSPin as Byte = 13 Sub Main() Dim N as Byte, Val as Integer, SPISetUpByte as Byte, SPIChannel as Byte Dim BiPolar as Byte Dim Str as String *10 Str = " ... " ' used for debugging Call OpenSerialPort(1, 19200) SPISetUpByte = 1 SPIChannel = 1 BiPolar = 0 ' unipolar measurements Call OpenSPI(SPIChannel, SPISetUpByte, CSPin) Do For N = 0 to 10 Val = TLC2543SingleMeas(SPIChannel, N, BiPolar) ' SPIChannel, Channel N, Bipolar Call PutB(N) Call PutStr(Str) Call PutI(Val) Call NewLine() Call Sleep(0.5) Next Call TLC2543Sleep(SPIChannel) Call Sleep(5.0) Loop End Sub Function TLC2543SingleMeas(ByVal SPIChannel as Byte, _ ByVal Channel as Byte, _ ByVal BiPolar as Byte) _ as Integer Dim PutData(1 to 2) as Byte, GetData(1 to 2) as Byte PutData(1) = Channel * 16 + bx00001100 + BiPolar ' channel plus 16-bit mode + BiPolar PutData(2) = bx00000000 Call SPICmd(SPIChannel, 2, PutData(1), 0, GetData(1)) ' send command byte followed by dummy byte Call Sleep(0.05) ' receive 16 bit result Call SPICmd(SPIChannel, 0, PutData(1), 2, GetData(1)) ' Call PutB(GetData(1)) ' Call PutByte(Asc(" ")) ' Call PutB(GetData(2)) ' Call NewLine() ' Put the high and low bytes together. Result is in lower 12-bits. TLC2543SingleMeas = CInt(GetData(1)) * 16 + CInt(GetData(2))\16 End Function Sub TLC2543Sleep(ByVal SPIChannel as Byte) Dim PutData(1 to 2) as Byte, GetData(1 to 2) as Byte PutData(1) = &H0e * 16 + bx00001100 ' sleep plus 16-bit mode PutData(2) = bx00000000 Call SPICmd(SPIChannel, 2, PutData(1), 0, GetData(1)) ' send command byte followed by dummy byte End Sub Ok, questions I have: 1. What is the purpose of the "PutData(2)" and "GetData(2)" bytes that are defined? I cannot seem to understand why these are part of the code, as it appears they aren't used. 2. It seems that there are a few commands that he is using that aren't listed in the library of commands (in the basicx documents). Examples: openserialport, putb, puti, putstr, etc. Is this code just for reference, or an actual working example? 3. What is the purpose of the TLC2543Sleep function that he describes towards the end of the program? I am taking this step by step, so I appreciate all of your help regarding this! |
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TLC2543 example questions
Started by ●September 19, 2002
Reply by ●September 20, 20022002-09-20
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To answer a few of your questions: 1) PutData(2) and GetData(2) are the second bytes that are being sent and received, remember that you are clocking 16 bits of data. If you tell SPICmd to clock 2 bytes starting at PutData(1), it will send PutData(2) as the second byte. 2) I'm not sure about the others, but I know that OpenSerialPort is a sample routine by NetMedia that contains alot of functions you can incorporate into your code. I don't know about #3. Hope that helps! JeremyB. |
