Hi, I'm trying to get rs232 to work on our custom hardware which uses the K60F120M cpu. For uart 4 we have TX = PTE24 and RX = PTE25. To get this to work I made the following change in our BSP in init_gpio.c:
case 4:
pctl = (PORT_MemMapPtr)PORTE_BASE_PTR;
if (flags & IO_PERIPHERAL_PIN_MUX_ENABLE)
{
pctl->PCR[24] = 0 | PORT_PCR_MUX(3) | PORT_PCR_DSE_MASK; //TX
pctl->PCR[25] = 0 | PORT_PCR_MUX(3) | PORT_PCR_DSE_MASK; //RX
}
if (flags & IO_PERIPHERAL_PIN_MUX_DISABLE)
{
pctl->PCR[24] = 0;
pctl->PCR[25] = 0;
}
if (flags & IO_PERIPHERAL_CLOCK_ENABLE)
{
/* start SGI clock */
sim->SCGC1 |= SIM_SCGC1_UART4_MASK;
}
if (flags & IO_PERIPHERAL_CLOCK_DISABLE)
{
/* stop SGI clock */
sim->SCGC1 &= (~ SIM_SCGC1_UART4_MASK);
}
break;
I've then made a small example to test if it works:
#define RS485_CHANNEL "ittye:"
...
MQX_FILE_PTR rs485_dev = NULL;
char data_buffer[6] = {0};
data_buffer[0] = 'H';
data_buffer[1] = 'E';
data_buffer[2] = 'L';
data_buffer[3] = 'L';
data_buffer[4] = 'O';
rs485_dev = fopen( RS485_CHANNEL, NULL );
uint32_t baud = 19200;
ioctl(rs485_dev, IO_IOCTL_SERIAL_SET_BAUD, &baud);
write( rs485_dev, data_buffer, strlen(data_buffer) );
fflush( rs485_dev );
What happens when I run this code is that what I send on the TX is also what I get on RX (but inverted) even though it isn't connected to anything else than the logic analyzer I use to meassure. So it seems that somehow, everything I send out I recieve an inverted copy of. How can I get rid of this behaviour? Did I do anything wrong when changing init_gpio.c?
Just to clarify, this is the result from my logic analyzer (where the top signal is tx and the bottom rx):
Hi Jesper:
Please check the UARTx_S2 register, there is one bit to control the Receive data Inversion.
Have a great day,
Daniel
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