I am trying to set up the SC16IS762 dual UART in a polled mode and I am expecting to be able to read several bytes from the receiver FIFO.
There is no flow control set up and RTSA, RTSB, CTSA and CTSB are not connected.
I am able to send several bytes using the Tx FIFO, but cannot get the Rx FIFO to accept more than one character.
I am using SPI to communicate with the device.
First, I initialise the device
#define E_SC16IS762_CHAN_SEL_A 0
#define E_SC16IS762_CHAN_SEL_B 1
// Clear contents of transmit and receive FIFOs, resets FIFO level logic and enables transmit and receive FIFOs
SC16IS762_SPI_WriteByte (E_SC16IS762_CHAN_SEL_A, FCR, 0x07);
SC16IS762_SPI_WriteByte (E_SC16IS762_CHAN_SEL_B, FCR, 0x07);
// Disable interrupts on FIFO levels as we want to pollSC16IS762_SPI_WriteByte (E_SC16IS762_CHAN_SEL_A, IER, 0x00); SC16IS762_SPI_WriteByte (E_SC16IS762_CHAN_SEL_B, IER, 0x00);
// Set GPIO lines to output
SC16IS762_SPI_WriteByte (E_SC16IS762_CHAN_SEL_A, IODir, 0xFF); // all o/p
SC16IS762_SPI_WriteByte (E_SC16IS762_CHAN_SEL_A, IOState, 0x00); // all 0
// disable interrupts on GPIO state change
SC16IS762_SPI_WriteByte (E_SC16IS762_CHAN_SEL_A, IOIntEna, 0x00);}
and then the two UART channels.
// enable FIFO mode and set Rx trigger to 56
SC16IS762_SPI_WriteByte (channel, FCR, 0x81);// Set Extra Features all off
SC16IS762_SPI_WriteByte (channel, EFCR, 0x00);
// 0x80 to program baud rate
SC16IS762_SPI_WriteByte (channel, LCR, 0x80);// divisor LSB
SC16IS762_SPI_WriteByte (channel, DLL, (baudRate[rate] & 0xFF));
// divisor MSB
SC16IS762_SPI_WriteByte (channel, DLH, (baudRate[rate] >> 8);
// access EFR register
SC16IS762_SPI_WriteByte (spiModule, pDev->channel, LCR, 0xBF);// disable enhanced registers
SC16IS762_SPI_WriteByte (spiModule, pDev->channel, EFR, 0X00);
// 8 data bit, 1 stop bit, no parity
SC16IS762_SPI_WriteByte (spiModule, pDev->channel, LCR, 0x03, 1);
I have the dual UART on our own card with a crystal attached to pin XTAL1, XTAL2 is not connected.
I have connected TXA to RXB and vice versa.
I have a test application that sets both channels up with the same baud rate and then sends four bytes of data to one channel and reads it back on the other
uint32_t test1 = 0xAA55AA55;
uint32_t test5 = 0x0F0AF50D;
BSP_RS422_SendData(ch1, (uint8_t *)&test1, 4);
BSP_RS422_ReadData(ch2, rxBuff, 16);
ARM_printf("Received 0x%x\n", *(uint32_t *)rxBuff);
BSP_RS422_SendData(ch2, (uint8_t *)&test5, 4);
BSP_RS422_ReadData(ch1, rxBuff, 16);
ARM_printf("Received 0x %x\n", *(uint32_t *)rxBuff);
I have an oscilloscope set up on the output and see the full four bytes transmitted.
When I inspect the RXLVL register, it contains the value 1 and the RHR contains the first byte transmitted.
Please can someone suggest what I have missed in the setup.