Release notes?

[dkossman]

This is exactly what I was looking for - I have an Adafruit 2x16 I2C backpack that I want to talk to from C. I tried to build this code on a Pi running Raspbian, but got a ton of errors - is this not compatible with Raspbian? Or is there some prerequisite that I'm missing?

thx

---

pi@raspberrypi ~/rpi_lcd $ uname -a
Linux raspberrypi 3.6.11+ #371 PREEMPT Thu Feb 7 16:31:35 GMT 2013 armv6l GNU/Linux

pi@raspberrypi ~/rpi_lcd $ make
gcc -Wall -Wextra -Werror -g -o lcd lcd.c
In file included from rpii2c.h:35:0,
from rpii2c.c:26,
from mcp.h:33,
from mcp.c:33,
from lcd.h:36,
from lcd.c:26:
/usr/include/linux/i2c.h:67:8: error: redefinition of ‘struct i2c_msg’
/usr/include/linux/i2c-dev.h:38:8: note: originally defined here
/usr/include/linux/i2c.h:125:7: error: redefinition of ‘union i2c_smbus_data’
/usr/include/linux/i2c-dev.h:90:7: note: originally defined here
In file included from smbus.c:25:0,
from rpii2c.h:37,
from rpii2c.c:26,
from mcp.h:33,
from mcp.c:33,
from lcd.h:36,
from lcd.c:26:
smbus.h:29:14: error: conflicting types for ‘i2c_smbus_access’
/usr/include/linux/i2c-dev.h:161:21: note: previous definition of ‘i2c_smbus_access’ was here
In file included from rpii2c.h:37:0,
from rpii2c.c:26,
from mcp.h:33,
from mcp.c:33,
from lcd.h:36,
from lcd.c:26:
smbus.c: In function ‘i2c_smbus_access’:
smbus.c:48:12: error: assignment from incompatible pointer type [-Werror]
smbus.c: At top level:
smbus.c:57:7: error: redefinition of ‘i2c_smbus_write_quick’
/usr/include/linux/i2c-dev.h:174:21: note: previous definition of ‘i2c_smbus_write_quick’ was here
smbus.c:62:7: error: redefinition of ‘i2c_smbus_read_byte’
/usr/include/linux/i2c-dev.h:179:21: note: previous definition of ‘i2c_smbus_read_byte’ was here
smbus.c:74:7: error: redefinition of ‘i2c_smbus_write_byte’
/usr/include/linux/i2c-dev.h:188:21: note: previous definition of ‘i2c_smbus_write_byte’ was here
smbus.c:80:7: error: redefinition of ‘i2c_smbus_read_byte_data’
/usr/include/linux/i2c-dev.h:194:21: note: previous definition of ‘i2c_smbus_read_byte_data’ was here
smbus.c:93:7: error: redefinition of ‘i2c_smbus_write_byte_data’
/usr/include/linux/i2c-dev.h:204:21: note: previous definition of ‘i2c_smbus_write_byte_data’ was here
smbus.c:101:7: error: redefinition of ‘i2c_smbus_read_word_data’
/usr/include/linux/i2c-dev.h:213:21: note: previous definition of ‘i2c_smbus_read_word_data’ was here
smbus.c:114:7: error: redefinition of ‘i2c_smbus_write_word_data’
/usr/include/linux/i2c-dev.h:223:21: note: previous definition of ‘i2c_smbus_write_word_data’ was here
smbus.c:122:7: error: redefinition of ‘i2c_smbus_process_call’
/usr/include/linux/i2c-dev.h:232:21: note: previous definition of ‘i2c_smbus_process_call’ was here
smbus.c:134:7: error: redefinition of ‘i2c_smbus_read_block_data’
/usr/include/linux/i2c-dev.h:245:21: note: previous definition of ‘i2c_smbus_read_block_data’ was here
smbus.c:149:7: error: redefinition of ‘i2c_smbus_write_block_data’
/usr/include/linux/i2c-dev.h:260:21: note: previous definition of ‘i2c_smbus_write_block_data’ was here
smbus.c:167:7: error: redefinition of ‘i2c_smbus_read_i2c_block_data’
/usr/include/linux/i2c-dev.h:278:21: note: previous definition of ‘i2c_smbus_read_i2c_block_data’ was here
smbus.c:188:7: error: redefinition of ‘i2c_smbus_write_i2c_block_data’
/usr/include/linux/i2c-dev.h:298:21: note: previous definition of ‘i2c_smbus_write_i2c_block_data’ was here
smbus.c:203:7: error: redefinition of ‘i2c_smbus_block_process_call’
/usr/include/linux/i2c-dev.h:314:21: note: previous definition of ‘i2c_smbus_block_process_call’ was here
cc1: all warnings being treated as errors
make: *** [lcd] Error 1

[dkossman]

it appears that the code will only compile if you remove i2c-dev-tools:
sudo apt-get remove i2c-dev-tools

this is problematic.

[symptog]

ok
i'm using rasbian and there is no i2c-dev-tools, i think you meant i2c-tools ;)
so i removed the smbus from the dir and now i'm using the i2c_smbus functions from i2c-tools via #include <i2c-dev.h>
i pushed it and added some things to the readme.

get an update from the repo and
sudo apt-get install i2c-tools libi2c-dev

i think that should fix the problem

[dkossman]

Sorry for the typo re: i2c-tools, and thanks very much for the update - works like a charm now. Your technique of including code from within .c and .h files is a bit unorthodox, though :-). If I have time (doubtful) I'll take a look at untangling this and having the Makefile generate a more conventional library that can be installed in /usr/local/lib and referenced at link time. In the meantime, it works. Can't argue with success!

[symptog]

thanks, its my 1st "lib" ^^

[dkossman]

fyi - to set this up as a library:

1. change all instances of #include "xxx.c" to #include "xxx.h"
2. change the Makefile to something like:

SRCS = lcd.c mcp.c rpii2c.c
OBJS = $(patsubst %.c, %.o, $(SRCS))
HDRS = $(patsubst %.c, %.h, $(SRCS))
PROG = lcdtest

CC=gcc
CCFLAGS=-Wall -Wextra -Werror -g

default: $(PROG)

liblcd.a: $(OBJS)
ar rcs $@ $^
ranlib $@

$(PROG): lcdtest.o $(HDRS) liblcd.a Makefile
$(CC) $(CCFLAGS) -o $@ lcdtest.o liblcd.a

clean:
rm -f $(OBJS) $(PROG) liblcd.a