Hy, I use Cubietruck / Armbian I have a problem with I2C connecting to an Arduino. my Python program returns me an error when I use the SMBus module :
read_byte_data the function (address, reg) bug while writing functions work well.
here is my Arduino code :
#include <Wire.h>
#include <LiquidCrystal.h>
#include <string.h>
#include <ctype.h>
const int RS = 12;
const int E = 11;
const int D4 = 5;
const int D5 = 4;
const int D6 = 3;
const int D7 = 2;
LiquidCrystal lcd(RS,E,D4,D5,D6,D7);
#define SLAVE_ADDRESS 0x12
byte regs[3];
int regIndex=0;
byte lastExecReq = 0x00;
char message[20];
void setup (void){
regs[0] = 0x00;
regs[1] = 0x00;
regs[2] = 0x00;
Wire.begin(SLAVE_ADDRESS);
Wire.onReceive(receiveEvent);
Wire.onRequest(requestEvent);
Serial.begin(9600);
lcd.begin(20,4);
lcd.print ("LCD OK");
sprintf(message,"Bus I2C 0x%02x Ready",SLAVE_ADDRESS);
Serial.println(message);
lcd.setCursor(0,1);
lcd.print(message);
}
void loop(void){
if (regs[0]==0x00){
delay(100);
return;
}
switch(regs[0]){
case 0x01 : break;
case 0x02 : break;
case 0x03 :
if (regs[1]>0){
lcd.setCursor(0,2);
lcd.print("Start ... ");
}else{
lcd.setCursor(0,2);
lcd.print("Stop ... ");
}
break;
}
}
void receiveEvent(int byteCount){
int byteCounter = 0;
while (byteCounter<byteCount){
byte b = Wire.read();
byteCounter +=1;
if (byteCounter == 1){
regIndex = b;
}
else{
switch(regIndex){
case 0 :
regs[0] = b;
lastExecReq = b;
break;
case 1:
regs[1]=b;
break;
case 2:
regs[2]=b;
break;
}
}
}
}
void requestEvent(){
switch(regIndex){
case 0x00:
switch (lastExecReq){
case 0x01:
Wire.write(0x03);
break;
case 0x02:
Wire.write(regs[1]+regs[2]);
break;
default : Wire.write(0xFF);
}
break;
default: Wire.write(0xFF);
}
}
and here Python
#!/usr/bin/python
import re
import smbus
import time
address = 0x12
class Bus_I2C(object):
def __init__(self,address,busnum=1,debug=False):
self.address = address
self.bus = smbus.SMBus(busnum)
self.debug = debug
def errMsg(self):
print("access error 0x%02X: check your I2C address")%self.address
return -1
def write8(self,reg,value):
try:
self.bus.write_byte_data(self.address,reg,value)
if self.debug :
print("I2C : write 0x%02X in the reg 0x%02X")%(value,reg)
except IOError,err:
return self.errMsg()
def writeList(self,reg,list):
try:
if self.debug:
print("I2C : write a list in the reg 0x%02X:")%reg
print(list)
self.bus.write_i2c_block_data(self.address,reg,list)
except IOError,err:
return self.errMsg()
def readU8(self,reg):
try:
result=self.bus.read_byte_data(self.address,reg)
#result=self.bus.read_byte(self.address,reg)
if self.debug:
print("I2C : device 0x%02X returned 0x%02X from reg 0x%02X")%(self.address,result,reg)
return result
except IOError,err:
return self.errMsg()
i2c = Bus_I2C(address,1,True)
print("///////////// 0x01 in reg 0")
i2c.write8(0,0x01)
time.sleep(0.200)
print("///////////// read reg ...")
print(i2c.readU8(0x00))
time.sleep(0.100)
print("///////////// start LCD ...")
i2c.write8(0x01,1)
time.sleep(0.02)
i2c.write8(0x00,0x03)
time.sleep(0.100)
time.sleep(5)
print("///////////// stop LCD ...")
i2c.write8(0x01,0)
time.sleep(0.02)
i2c.write8(0x00,0x03)
time.sleep(0.100)
where is the bug ?
thank for your help
geka
