tc520.c

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#include <drv/tc520.h>
#include <drv/timer.h>

#include <hw_tc520.h>

#include <cfg/macros.h>
#include <cfg/compiler.h>

#include <drv/ser.h>

static Serial *spi_ser;

#define TC520_CONVERSION_TIMEOUT ms_to_ticks(1000)
#define INIT_LOAD_VALUE 0x00

tc520_data_t tc520_read(void)
{
    /* Start convertion and wait */
    CE_LOW();
    ticks_t start = timer_clock();
    do
    {
        /* timeout check */
        if (timer_clock() - start >= TC520_CONVERSION_TIMEOUT)
        {
            ASSERT(0);
            CE_HIGH();
            return TC520_MAX_VALUE;
        }
    }
    while(DV_LOW());

    start = timer_clock();
    do
    {
        /* timeout check */
        if (timer_clock() - start >= TC520_CONVERSION_TIMEOUT)
        {
            ASSERT(0);
            CE_HIGH();
            return TC520_MAX_VALUE;
        }
    }
    while(DV_HIGH());

    /* Ok, convertion finished, read result */
    CE_HIGH();
    READ_LOW();

    /* RX buffer could be dirty...*/
    ser_purge(spi_ser);

    /* I/O buffer */
    uint8_t buf[3] = "\x0\x0\x0";

    /* Dummy write to activate recv */
    ser_write(spi_ser, buf, sizeof(buf));
    ser_drain(spi_ser);
    READ_HIGH();

    /* recv */
    ASSERT(ser_read(spi_ser, buf, sizeof(buf)) == sizeof(buf));

    tc520_data_t res;

    /* Recompose data */
    res = (((tc520_data_t)(buf[0] & 0x3F)) << 10) | (((tc520_data_t)buf[1]) << 2) | (((tc520_data_t)buf[2]) >> 6);

    #define OVERRANGE_BIT BV(7)
    /* Handle overrange bit as 17th bit */
    if (buf[0] & OVERRANGE_BIT)
        res |= BV32(16);

    return res;
}


void tc520_init(Serial *spi_port)
{
    spi_ser = spi_port;
    /* init io ports */
    TC520_HW_INIT;
    /* Send initial load value */
    LOAD_LOW();
    ser_putchar(INIT_LOAD_VALUE, spi_ser);
    ser_drain(spi_ser);
    LOAD_HIGH();
}