STMPE811 Touch Controller example

stmpe811-example.c

/*                                                                                                  
 * Look at using the i2c functions in the utility library                                                   
 *                                                                                                  
 * Copyright (c) 2015, Chuck McManis, all rights reserved.                                          
 *                                                                                                  
 * This example talks to the XY screen touch controller
 * (its a peripheral already on the board) and prints
 * the co-ordinates pressed on the serial port.
 */

#include <stdint.h>
#include <stdio.h>
#include <utilloc3/stm32/console.h>
#include <utilloc3/stm32/term.h>
#include <utilloc3/stm32/pins.h>
#include <utilloc3/stm32/clock.h>
#include <utilloc3/stm32/i2c.h>
#include "stmpe811.h"

/*
 * Data about the chip on the Discovery board ...
 * USER Manual:
 *          i2c (3) SCLK - PA8
 *          i2c (3) SDA - PC9
 *          Interrupt - PA15
 *
 */

/*
 * Initialization lifted from the App Note #2807
 */
uint8_t init_sequence[] = {
        STMPE_REG_SYS_CTRL2,            0x0c,
        STMPE_REG_INT_EN,               0x07, /* group reading */
        STMPE_REG_ADC_CTRL1,            0x49,
        STMPE_REG_ADC_CTRL2,            0x01,
        STMPE_REG_GPIO_AF,              0x00,
        STMPE_REG_TSC_CFG,              0x9a,
        STMPE_REG_FIFO_TH,              0x5,
        STMPE_REG_FIFO_STA,             0x1,    /* reset the FIFO */
        STMPE_REG_FIFO_STA,             0x0,
        STMPE_REG_TSC_FRACTION_Z,       0x7,
        STMPE_REG_TSC_I_DRIVE,          0x1,
        STMPE_REG_TSC_CTRL,               1,
        STMPE_REG_INT_STA,              0xff,
        STMPE_REG_INT_CTRL,              0x1,
        0,      0
};


int
main(void)
{
    uint32_t rval;
    int     chan;
    int     i;
    
    clock_setup(168000000, 8000000);
    console(PA9, PA10, 115200);

    printf("I2C Example code.\n");
    printf("Version 0.5\n");
    chan = i2c_master(PA8, PC9, I2C_400KHZ);
    pin_input(PA15, PXX);   /* interrupt pin */
    pin_attributes(PIN_PULLUP | PIN_OPENDRAIN, PA8, PC9, PA15, PXX);

    pin_output(PD10, PD14, PXX);
    pin_clear(PD10, PD14, PXX); 

    i = read_register_i2c(chan, STMPE_ADDR, STMPE_REG_CHIP_ID, &rval, 2);
    if (i < 0) {
        printf("Touch Screen controller didn't respond.\n");
        while (1);
    }
    if (rval != 0x811) {
        printf("I don't think this is an STMPE811, expected 0x811 but got 0x%x\n",
                        (unsigned int) rval);
        while(1);
    }
    printf("Initializing touch screen controller.\n");
    for (i = 0; init_sequence[i] != 0; i += 2) {
        printf("Init: 0x%x => 0x%x\n", (unsigned int) init_sequence[i],
                                       (unsigned int) init_sequence[i+1]);
        write_register_i2c(chan, STMPE_ADDR, init_sequence[i], init_sequence[i+1], 1);
        if (init_sequence[i] == STMPE_REG_ADC_CTRL1) {
                msleep(2);
        }
    }

    printf("Init sequence complete, waiting for touch events\n");
    while(1) {
        uint32_t        reg;
        uint32_t        touch_xyz;
        uint32_t        cnt;
        uint32_t        x, y;
        int             err;

        /* wait for an event (you could take an interrupt here) */
        while (pin_get(PA15, PXX) == 1) ;
        err = read_register_i2c(chan, STMPE_ADDR, STMPE_REG_INT_STA, &reg, 1);
        if (err < 0) {
            printf("i2c crashed.\n");
            while (1) ;
        }

        /* call out the events detected, we care about 'touch' and stuff
         * showing up in the FIFO, we alert on FIFO overflow or filling
         * up completely.
         */
        if (reg & 0x1) {
            printf("Touch detect!\n");
        }
        if (reg & 0x2) {
            read_register_i2c(chan, STMPE_ADDR, STMPE_REG_FIFO_SIZE, &cnt, 1);
            x = 0; y = 0;
            /* Read value out of the fifo */
            while (cnt-- > 0) {
                read_register_i2c(chan, STMPE_ADDR, STMPE_REG_TSC_DATA_XYZ, &touch_xyz, 4);
            }
            /* only keep the last one, its a demo */
            y = (touch_xyz >> 8) & 0xfff;
            x = (touch_xyz >> 20) & 0xfff;
            printf("Touched Point X: %d, Y: %d\n", (int) x, (int) y);
            read_register_i2c(chan, STMPE_ADDR, STMPE_REG_FIFO_SIZE, &cnt, 1);
        }
        if (reg & 0x4) {
            printf("Warning: FIFO overflow, lost some touch points.\n");
        }
        if (reg & 0x8) {
            printf("Warning: FIFO FULL!, lost some touch points.\n");
        }
        /* reset all the bits that were set */
        write_register_i2c(chan, STMPE_ADDR, STMPE_REG_INT_STA, reg, 1);
    }
}