After buying an HD44780 compatible LCD together with an I2C interface board (which has an PCF8574T soldered on it) I tried to output some text in C on it but the display just stayed black - or after changing some GPIOs, it stayed blue. I measured every pin of the PCF8574T and got the following scheme:
PCF8574T <-> HD44780 P0 -- RS P1 -- R/W P2 -- EN P4 -- DB4 P5 -- DB5 P6 -- DB6 P7 -- DB7 R/W should be mapped to GND if the HD44780 should not talk back to the CPU.
This weekend, I played around a bit with Lua and C. My aim was to understand the Lua basics, embed the script engine into C and be able to even call a C function from Lua.
With Google and a lot of documentation spread around the web this was a fairly easy task. The result are 2 short files. First file is the C-code main.c which initializes Lua, registers the C-function which will be later called by Lua and then executes the Lua-script.
Hi,
if you’re writing a kernel module and get the following error:
*** Warning: "symbol_name" [/path/to/module] is COMMON symbol Than its possible that you simply forgot to mark it as static. Thanks for this fix goes to Brad Aisa from the website KernelTrap.
Bye, Sven
Hi,
Task
We have a included struct called counter and we don’t want to assign the initial values in the main function.
Solution
source.c
#include <counters.h> struct counter_t counter = { .max_value = 1234, }; int main(void) { return(0); } Bye, Sven
Hi there,
Task
We have a Makefile, we have a C file, now we want update a timestamp whenever the C file is compiled.
Solution
Makefile
CFLAGS += -D__TIMESTAMP__=\""$(shell date +%Y/%m/%d\ %H:%M:%S)"\" source.c
include <stdio.h> #ifndef __TIMESTAMP__ #define __TIMESTAMP__ "NO TIMESTAMP DEFINED" #endif /* __TIMESTAMP__ */ int main(void) { printf("my tool (TS: %s)\n", __TIMESTAMP__); return(0); } Output
~$ ./source my tool (TS: 2008/11/06 09:55:22) Bye, Sven
