I am working with St7789v driver based RGB565 Display . I have chosen SPI21 configured at 8Mhz and if I send 15 bytes chunk of image bitmaps, I can see the image in the display .
if i increase it to more than 15 bytes , the image is distorted and showing like garbage .
I have kept the image bitmaps in RAM and trying to display the image .
even if I send 15 bytes chunks and decrease the SPI clock to 4Mhz , this time also I can not see the actual image .
here is the code for reference
static struct spi_config spi_cfg = {
.frequency = 8000000,
.operation = SPI_WORD_SET(8) | SPI_TRANSFER_MSB | SPI_OP_MODE_MASTER,
.slave = 0,
.cs = NULL,
};
int spi_send(const uint8_t *data, size_t len,char continuous)
{
struct spi_buf tx_buf = {
.buf = (void *)data,
.len = len,
};
struct spi_buf_set tx = {
.buffers = &tx_buf,
.count = 1,
};
gpio_pin_set(spi_cs_spec.port, spi_cs_spec.pin, 0); // CS = 0 to select the device
int ret = spi_write(spi_dev, &spi_cfg, &tx);
if (continuous == 0)
gpio_pin_set(spi_cs_spec.port, spi_cs_spec.pin, 1); // CS = 1 to deselect the device
if (ret)
{
LOG_ERR("SPI write failed: %d", ret);
}
return ret;
}
Function used to display the image
static void DE_vDrawBuffer(const Position_t *pos, uint8_t *buffer, size_t bufSize)
{
const uint32_t w = pos->width;
const uint32_t h = pos->height;
const uint32_t total = w * h * 2u; // RGB565 = 2 bytes/pixel
const int x0 = pos->x;
const int y0 = pos->y;
const int x1 = x0 + (int)w - 1;
const int y1 = y0 + (int)h - 1;
DE_vSetWindow(x0, y0, x1, y1);
write_command(ST77XX_RAMWR); // 0x2C: start GRAM write
int readData = 0;
#define CHUNK_SIZE (12)
//kb TOBO: why can not i increase above 15 bytes of chunk size?
//if i send above 15 bytes, the display shows garbage
uint8_t temp[CHUNK_SIZE];
while (readData <= total)
{
int toRead = total - readData > CHUNK_SIZE ? CHUNK_SIZE : total - readData;
memcpy(temp, &buffer[readData], toRead);
write_data(temp, toRead,1);
readData += toRead;
}
SetCSHigh();
}
