1 Attachment(s)
Problem with I2C EEPROM addressing
Hello - I have a strange problem when trying to access an EEPROM at a certain address. I have a string of five 24LC256 EEPROMs all sharing the same clock and data line. On the first 4, I am storing the position of 4 servos with the position value converted to a byte-sized variable. On the last one, I am storing the state of a relay (1 or 0). The EEPROMs are addressed 000, 001, 010, 011 and 100. I have no problem reading and writing to the first 3 EEPROMs and the last one, but for some reason, I can not read or write to the 4th EEPROM (011). I have tried swapping EEPROMs around and have determined that there is something to do with that address. My code is pretty straight forward - record mode = read the positions of the 4 servos and relay convert to byte-size (servos) and store the data. Playback mode = read the data convert it to word-sized numbers (for servos) and send it out. The same code is used for all 4 servos. 1, 2 and 3 work fine, 4 just pegs out during playback. The servo #4, when under manual control, responds fine. Anyone have any idea what my problem could be? Attached is a drawing showing my EEPROM layout. I thought it might be a timing issue but why does it only affect #4 and not #5?
PBP 2.5 and 877A PIC.
Here are some code snipetts:
Posit var word
Posit1 var word
Posit2 var word
Posit3 var word
Posit4 var word
PVal var byte
'EEPROM 1 will contain posit data for Servo 1
EChip1W CON %10100000 'Write mode for EEPROM 1
EChip1R CON %10100001 'Read mode for EEPROM 1
'EEPROM 2 will contain posit data for Servo 2
EChip2W CON %10100010 'Write mode for EEPROM 2
EChip2R CON %10100011 'Read mode for EEPROM 2
'EEPROM 3 will contain posit data for Servo 3
EChip3W CON %10100100 'Write mode for EEPROM 3
EChip3R CON %10100101 'Read mode for EEPROM 3
'EEPROM 4 will contain posit data for Servo 4
EChip4W CON %10100110 'Write mode for EEPROM 4
EChip4R CON %10100111 'Read mode for EEPROM 4
'EEPROM 5 will contain data for Relay
EChip5W CON %10101000 'Write mode for EEPROM 5
EChip5R CON %10101001 'Read mode for EEPROM 5
Record Mode Code Snipett---
gosub ReadPot1
pulsout servo1, posit1
pause 5
gosub ReadPot2
pulsout servo2, posit2
pause 5
gosub ReadPot3
pulsout servo3, posit3
pause 5
gosub ReadPot4
pulsout servo4, posit4
pause 5
if recordflag = 1 then 'store data
posit = (posit1 * 23) / 100 'convert to a value < 255
pval = posit 'put into a byte variable
I2CWRITE DPIN, CPIN, EChip1W, Addr, [PVal] 'write it out
posit = (posit2 * 23) / 100
pval = posit
I2CWRITE DPIN, CPIN, EChip2W, Addr, [PVal]
posit = (posit3 * 23) / 100
pval = posit
I2CWRITE DPIN, CPIN, EChip3W, Addr, [PVal]
posit = (posit4 * 23) / 100
pval = posit
I2CWRITE DPIN, CPIN, EChip4W, Addr, [PVal]
if RelaySw = 1 then
pval = 1
else
pval = 0
endif
I2CWRITE DPIN, CPIN, EChip5W, Addr, [PVal]
addr = addr + 1
endif
PlayBack Mode Code Snipett---
high PlayLED
read 16, Lastaddr.byte0
read 17, lastaddr.byte1
for addr = 1 to lastaddr
i2cread dpin, cpin, echip1r, addr, [pval]
posit = pval * 4 'multiply by 4.03 to convert back to word
posit = posit + ((pval * 3) / 100)
pulsout servo1, posit
pause 5
i2cread dpin, cpin, echip2r, addr, [pval]
posit = pval * 4
posit = posit + ((pval * 3) / 100)
pulsout servo2, posit
pause 5
i2cread dpin, cpin, echip3r, addr, [pval]
posit = pval * 4
posit = posit + ((pval * 3) / 100)
pulsout servo3, posit
pause 5
i2cread dpin, cpin, echip4r, addr, [pval]
posit = pval * 4
posit = posit + ((pval * 3) / 100)
pulsout servo4, posit
pause 5
i2cread dpin, cpin, echip5r, addr, [pval]
if pval = 0 then
low Relay
low RelayLED
else
high Relay
high RelayLED
endif
if SSRecBtn = 1 then
low Relay
low RelayLED
low PlayLED
pause 500
goto Start
endif
next
