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/*
*i2ctest.c
* Raspberry Pi I2C test using wiringPi library.
*
*Copyright (c) Nahid Alam. <nahid.mahfuza.alam@gmail.com>
***********************************************************
*i2ctest is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* i2ctest is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
***********************************************************
*/
#include <stdio.h>
#include <wiringPi.h>
#include <wiringPiI2C.h>
uint8_t solve_challenge(uint8_t arg) {
return (arg >> 3) ^ (arg << 3);
}
uint8_t parse_int(const char *s) { // Convert string to hex
uint8_t result = 0;
int c;
if ('0' == *s && 'x' == *(s + 1)) {
s += 2;
while (*s) {
result = result << 4;
if (c = (*s - '0'), (c >= 0 && c <= 9)) result |= c;
else if (c = (*s - 'A'), (c >= 0 && c <= 5)) result |= (c + 10);
else if (c = (*s - 'a'), (c >= 0 && c <= 5)) result |= (c + 10);
else break;
++s;
}
}
return result;
}
int main(int argc, char *argv[]) {
int fd; // Linux filehandle to the i2c device
uint8_t challenge;
uint8_t response;
uint8_t i2c_addr;
if (argc != 2) {
printf("Usage: \n\ti2c_challenge <i2caddr>");
return 1;
}
i2c_addr = parse_int(argv[1]);
wiringPiSetup();
fd = wiringPiI2CSetup(i2c_addr); // Initialize the i2c protocol with the address
if (fd == -1) { // Failed to contact device
printf("Can't setup the I2C device\n");
return -1;
}
delay(1);
challenge = wiringPiI2CRead(fd);
response = solve_challenge(challenge);
wiringPiI2CWrite(fd, response);
return 0;
}