TS-8150-47XX KPAD

This header is designed to connect to the KPAD accessory which uses the odd DIO on this header to scan a 4x4 keypad. This example scans the KPAD and prints out the pressed character.

/* KPAD 4x4 keypad example code
 *
 * To compile, copy to the board and run:
 * 	gcc kpad.c -o kpad  */
 
#include <stdio.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
 
volatile uint16_t *syscon = 0;
 
// Map DIO 14,13,11,10,8,7,6,4 to "out" as bits 0:7
const int pins[8] = {14,13,11,10,8,7,6,4};
 
uint16_t peek16(uint16_t addr) 
{
    uint16_t value;
 
    if(syscon == 0) {
        int mem = open("/dev/mem", O_RDWR|O_SYNC);
        syscon = mmap(0,
            getpagesize(),
            PROT_READ|PROT_WRITE,
            MAP_SHARED,
            mem,
            0x80004000);
    }
 
    return syscon[addr/2];
}
 
void poke16(uint16_t addr, uint16_t value)
{
    if(syscon == 0) {
        int mem = open("/dev/mem", O_RDWR|O_SYNC);
        syscon = mmap(0,
            getpagesize(),
            PROT_READ|PROT_WRITE,
            MAP_SHARED,
            mem,
            0x80004000);
    }
 
    syscon[addr/2] = value;
}
 
void set_output(uint8_t out) 
{
    uint16_t val = peek16(0x10);
    int i;
 
    for (i = 0; i < 8; i++)
    {
        if(out & (1 << i)) val |= (1 << pins[i]);
        else val &= ~(1 << pins[i]);
    }
 
    poke16(0x10, val);
}
 
void set_ddr(uint8_t ddr) 
{    
    uint16_t val = peek16(0x18);
    int i;
 
    for (i = 0; i < 8; i++)
    {
        if(ddr & (1 << i)) val |= (1 << pins[i]);
        else val &= ~(1 << pins[i]);
    }
 
    poke16(0x18, val);
}
 
uint8_t get_input() 
{
    uint16_t val = peek16(0x20);
    uint8_t in = 0;
    int i;
 
    for (i = 0; i < 8; i++)
    {
        if(val & (1 << pins[i])) in |= (1 << i);
        else in &= ~(1 << i);
    }
 
    return in;
}
 
int main()
{
    uint8_t ddr = 0x0f;
    uint8_t out = 0xff;
    int row, col;
 
    char *keys[4][4] = {
        { "1", "2", "3", "UP" },
        { "4", "5", "6", "DOWN" },
        { "7", "8", "9", "2ND" },
        { "CLEAR", "0", "HELP", "ENTER" }
    };
 
    //set first 4 as outputs, last 4 as inputs
    set_ddr(ddr);
 
    while(1) {
        for(row = 0; row < 4; row++) {
            set_output(~(1 << row));
            usleep(50000);
            uint16_t in = get_input();
            for(col = 4; col < 8; col++) {
                if(~in & (1 << col)) {
                    // If we read it, sleep and read again to debounce
                    usleep(1000);
                    in = get_input();
                    if(~in & (1 << col)) {
                        printf("%s\n", keys[row][col - 4]);
                        fflush(stdout);
                    }
                }
            }
        }
    }
 
    return 0;
}