Class: Fubuki::SPI

Inherits:
Object
  • Object
show all
Defined in:
ext/fubuki/fubuki.c

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Object 



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# File 'ext/fubuki/fubuki.c', line 41

static VALUE spi_init(int argc, VALUE* argv, VALUE self) {
        VALUE bus, device;
        rb_scan_args(argc, argv, "02", &bus, &device);

        int bus_id = 0;
        switch (TYPE(bus)) {
        case T_FIXNUM:
                bus_id = NUM2UINT(bus);
                break;
        case T_NIL:
                break;
        default:
                rb_raise(rb_eTypeError, "not valid SPI bus id");
                break;
        }

        int device_id = 0;
        switch (TYPE(device)) {
        case T_FIXNUM:
                device_id = NUM2UINT(device);
                break;
        case T_NIL:
                break;
        default:
                rb_raise(rb_eTypeError, "not valid SPI device id");
                break;
        }

        char path[1000] = "";
        snprintf(path, 1000, "/dev/spidev%d.%d", bus_id, device_id);
        int fd = open(path, O_RDWR);
        if (fd < 0) {
                rb_raise(rb_eRuntimeError, "cannot open SPI device");
        }

        struct spi_malloc *ptr;
        Data_Get_Struct(self, struct spi_malloc, ptr);
        ptr->fd = fd;

        return self;
}

Instance Method Details

#close ⇒ Object 



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# File 'ext/fubuki/fubuki.c', line 174

static VALUE spi_close(VALUE self) {
        struct spi_malloc *ptr;
        Data_Get_Struct(self, struct spi_malloc, ptr);
        int fd = ptr->fd;
        if (fd < 0) {
                rb_raise(rb_eRuntimeError, "SPI device not opened");
        }

        close(fd);

        ptr->fd = -1;

        return Qtrue;
}

#transfer(*args) ⇒ Object 



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# File 'ext/fubuki/fubuki.c', line 83

static VALUE spi_transfer(int argc, VALUE* argv, VALUE self) {
        char error_message[1000] = "";
        int i = 0;
        int status = 0;

        struct spi_malloc *ptr;
        Data_Get_Struct(self, struct spi_malloc, ptr);
        int fd = ptr->fd;
        if (fd < 0) {
                rb_raise(rb_eRuntimeError, "SPI device not opened");
        }

        VALUE tx_data, speed_hz, delay_usec;
        rb_scan_args(argc, argv, "12", &tx_data, &speed_hz, &delay_usec);

        if (TYPE(tx_data) != T_ARRAY) {
                rb_raise(rb_eTypeError, "input data should be array of bytes");
        }

        int spi_speed = 1000000;
        switch (TYPE(speed_hz)) {
        case T_FIXNUM:
                spi_speed = NUM2UINT(speed_hz);
                break;
        case T_NIL:
                break;
        default:
                rb_raise(rb_eTypeError, "not valid SPI speed");
                break;
        }

        int spi_delay = 0;
        switch (TYPE(delay_usec)) {
        case T_FIXNUM:
                spi_delay = NUM2UINT(delay_usec);
                break;
        case T_NIL:
                break;
        default:
                rb_raise(rb_eTypeError, "not valid SPI delay");
                break;
        }

        long buf_len = RARRAY_LEN(tx_data);

        uint8_t *tx_buf = calloc(buf_len, sizeof(uint8_t));
        uint8_t *rx_buf = calloc(buf_len, sizeof(uint8_t));

        for (i = 0; i < buf_len; i++) {
                VALUE element = rb_ary_entry(tx_data, i);
                if (TYPE(element) != T_FIXNUM) {
                        snprintf(error_message, 1000, "input data should be array of bytes");
                        goto cleanup_buffer;
                }

                tx_buf[i] = (uint8_t)NUM2UINT(element);
        }

        struct spi_ioc_transfer tr = {
                .tx_buf = (unsigned long)tx_buf,
                .rx_buf = (unsigned long)rx_buf,
                .len = buf_len,
                .delay_usecs = spi_delay,
                .speed_hz = spi_speed,
                .bits_per_word = 8,
        };

        status = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);

        if (status < 1) {
                snprintf(error_message, 1000, "cannot send SPI message");
                goto cleanup_buffer;
        }

        VALUE rx_data = rb_ary_new2(buf_len);

        for (i = 0; i < buf_len; i++) {
                rb_ary_store(rx_data, i, UINT2NUM(rx_buf[i]));
        }

cleanup_buffer:
        free(tx_buf);
        free(rx_buf);

        if (strlen(error_message) > 0) {
                rb_raise(rb_eRuntimeError, "%s", error_message);
        }

        return rx_data;
}