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Forum Index : Microcontroller and PC projects : I2C AND MMBASIC
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| ratsac Newbie  Joined: 19/12/2011 Location: AustraliaPosts: 8 |
Hi just new to this forum and to maximite Computers Can anyone assit or redirect me in the use of I2C procol I am using mmbasic and a PCF8574 (8* i/o device). The commands I have used are I2CEN 10,100 (enables i2c ) I2CSEND 64,0,1,0 (should set ports to low) Doesn’t work I know about using the negitive –330 ohm resister –pcf8574 Has anyone had success with any I2C devices and mmbasic Thanks |
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| DuinoMiteMegaAn Senior Member  Joined: 17/11/2011 Location: AustraliaPosts: 231 |
RTC I2C "write" code snippet (courtesy of Ken) 720 REM I2CSEND i2caddr, 0, 1 , &h0
725 I2CSEND i2caddr, 0, 10, 0, 0, 0, seconds, minutes, hours, day, rtcwday, month, year 730 I2CDIS 770 ? "0=ok 1=nack 2=timeout"; MM.I2C <------ observe this code !!!! Another I2C "write" code snippet 460 ' Write Time to RTC
470 i2caddr = &h68 ' DS3231 I2C address 480 I2CEN 400,100 ' Enable I2C <--- high speed 100 ms timeout 490 I2CSEND i2caddr, 0, 8, &h0, seconds, minutes, hours, rtcwday, day, month, year 500 I2CDIS I2CEN 10,100 (enables i2c )
Only 10 KHz ? For I2C speed?
Make sure you got the proper pullups for the I2C ??? You need two of them. See the Maximite manual. 
Is this I2C device a 3.3 VDC device or a I2C 5 VDC device? Make sure the pullups are tied to the same device VCC
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| Olimex Senior Member Joined: 02/10/2011 Location: BulgariaPosts: 226 |
if A0,A1,A2 are wired to ground try: I2CSEND 32,0,1,0 |
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| ratsac Newbie Joined: 19/12/2011 Location: AustraliaPosts: 8 |
Thanks For assistance Have tried addresses 64 end 32 with no success repower pcf8574 with own +5v but alas still no success even raised speed and shorten bus will look for a logic alternative.javascript:AddSmileyIcon('  ') |
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| DuinoMiteMegaAn Senior Member Joined: 17/11/2011 Location: AustraliaPosts: 231 |
What are you using for pullups? Put this line of code after writing to your device. ? "0=ok 1=nack 2=timeout"; MM.I2C '<------ observe this code !!!!
And tell me what you got? |
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| ratsac Newbie Joined: 19/12/2011 Location: AustraliaPosts: 8 |
Have tried adding mm.i2c 10 I2CEN 100,300 20 I2CSEND 64,0,1,0 (ALSO 32 TRIED) 30 I2CDIS 40 ? "0=OK 1=NACK 2=TIMEOUT";MM.I2C THE RESULTS ARE ALWAYS THE SAME 0 0 2 0 2 0 2 EVEN IF I DISC I2C PORTS NO CHANGE NIL COMMUNICATIONS RESULT THE BOARD HAS 3 * 10KOHM PULLUP RESISTORS MOUNTED O0N BOARD RATSAC |
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| Olimex Senior Member Joined: 02/10/2011 Location: BulgariaPosts: 226 |
64 is not correct address for this device you have to remove the last R/W bit 0 from the address as it's add from MM-BASIC |
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TassyJim Guru  Joined: 07/08/2011 Location: AustraliaPosts: 6098 |
Are the three pullups connected to the address pins and V+? If so try 39 as the address (32 + 7) Jim VK7JH MMedit  MMBasic Help |
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| seco61 Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 205 |
Hi. First I will assume that the PCF 8574 is correctly connected (common ground with the Maximite, A0 - A2 connected to ground, SDA connected to IO pin 12 and pulled high by a 2.7K resistor to the Vcc pin of the device, SCL connected to IO pin 13 and pulled high by a 2.7K resistor to the Vcc pin of the device). The following code should set the output pins high, then read the state of the pins: 10 I2CEN 100,100 20 I2CSEND 32,0,1,&hff 30 ? "MM.I2C after send: "; MM.I2C 40 I2CRCV 32,0,1,port 50 ? "MM.I2C after recv: "; MM.I2C;", Data from port: ";HEX$(port) 60 I2CDIS 70 END Please post the output if you are still having issues. Regards Gerard Regards Gerard (vk3cg/vk3grs) |
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| ratsac Newbie Joined: 19/12/2011 Location: AustraliaPosts: 8 |
have tried the above program the responses i received are MM.I2C after send: 0 [4] 40 I2CRCV 32,0,1,port Error: Receive variable not found operates output in device ok also is there any difference when using ubw32 as nil result is given |
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crackerjack Senior Member Joined: 11/07/2011 Location: AustraliaPosts: 164 |
You need to define port as an array with length as to what you receive to expect back from the i2c device. So in the used example make line 5 something like this: [code] 5 Dim RDBuff(5) ' length according to the response expected from your device [/code] From the manual: [code] I2CRCV addr, bus_hold, rcvlen, rcvbuf [,sendlen, senddata [,sendata ....]] ---- Receive data from the I2C slave device with the optional ability to send some data first. 'addr' is the slave i2c address (note that 10 bit addressing is not supported). 'option' is a number between 0 and 3 1 = keep control of the bus after the command (a stop condition will not be sent at the completion of the command) 2 = treat the address as a 10 bit address 3 = combine 1 and 2 (hold the bus and use 10 bit addresses). 'rcvlen' is the number of bytes to receive. 'rcvbuf' is the variable to receive the data - this is a one dimensional array or if rcvlen is 1 then this may be a normal variable. The array subscript does not have to be zero and will be honoured; also bounds checking is performed. Optionally you can specify data to be sent first using 'sendlen' and 'senddat'. These parameters are used the same as in the I2CSEND command (ie, senddata can be a constant, an array or a string variable). Examples: I2CRCV &h6f, 1, 1, avar I2CRCV &h6f, 1, 5, anarray(0) I2CRCV &h6f, 1, 4, anarray(2), 3, &h12, &h34, &h89 I2CRCV &h6f, 1, 3, anarray(0), 4, anotherarray(0) The automatic variable MM.I2C will hold the result of the transaction. [/code] |
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| ratsac Newbie Joined: 19/12/2011 Location: AustraliaPosts: 8 |
THANKS FOR ALL YOUR VALUABLE ASSISTANCE SAC |
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