ARM Cortex-R4F RM48x MCU baud question

Hello Willy,

The SCI uses the 24-bit integer prescaler P value of BRSR register to select the required baud rates. If VCLK is 80MHz, the P values for 1200/2400/4800 baudrate are 4168/2082/1041.

baudrate = VCLK /((P+1) *16)

Please double check the frame format on your PC side
1. start bit: 1
2. data bit: 1 to 8
3. stop bit: 0 to 2
4. Parity: 0 or 1

We don't support HW flow control.

BTW, does other baudrate works: 9600, 115200, etc?

Hello

When VCLK=110MHz
I want to set the baud to 4800/2400/1200
And how much should P value be set?

Hello Willy,

If VCLK is 110MHz,

For 4800 baudrate: p=110*10^6/(16*4800)-1 = 1431

For 115200: p=110*10^6/(16*115200)-1 = 59

For 1200: p=110*10^6/(16*1200)-1 = 5728

TI has a code generation tool (HALCoGen) which can be used to generate lower level driver for TMS570/RMx devices. Here is the download side:

2061.HALCoGen04.05.02 selftest.zipHello QJ Wang

I used the version of HalCoGen is 4.05.02.

But when I want to use baud rate of 4800 and P value is set to 1431, I can only transfer data and cannot receive data.

And the attach file is my HalCoGen project file.

Hi Willy,

Please enable the RX interrupt and write a sciNotification() to read the RXed data:

1. set RX interrupt: Check the RX interrupt under SCI/LIN Global
2. enable SCI interrupt: check the VIM channel 13 (high level) and channel 27 (low level)
3. In your main()

unsigned char rxData[8];
void main(){
_enable_IRQ();
sciInit();

/** - Configure SCI to receive 8 bytes of Command information */
sciReceive(scilinREG, 8, rxData);
}

add sciNotifcation():

/** @fn void sciNotification(unsigned flags) */
void sciNotification(sciBASE_t *sci, unsigned flags)
{
/** - Get ready to receive the next Command */
sciReceive (scilinREG, 8, rxData);

/** send rxData back to terminal */
sciSend (scilinREG, 8, rxData);
}

Hello QJ Wang

I used this sub-function as below, and I used the version of HalCoGen is 4.05.02.

void sciSetBaudrate(sciBASE_t *sci, uint32 baud)
{
float64 vclk = 110.000 * 1000000.0;
uint32 f = ((sci->GCR1 & 2U) == 2U) ? 16U : 1U;
uint32 temp;
float64 temp2;

temp = (f*(baud));
temp2 = ((vclk)/((float64)temp))-1U;
temp2 = floor(temp2 + 0.5); /* Rounding-off to the closest integer */
sci->BRS = (uint32)((uint32)temp2 & 0x00FFFFFFU);
}
and this function OK for TX , Baudrate 115200/57600/38400....9600/4800/2400/1200
but for RX 115200/57600/38400....9600 OK , 4800/2400/1200 not OK

thanks

Hello Willy,

Didn't you receive anything for 4800/2400/1200? or you received something but they are not correct?
Can you share your code with me? Thanks

Hello QJ Wang

I do not receive anything for baud rate set 4800/2400/1200.
The code is as follows:

void sciSetBaudrate(sciBASE_t *sci, uint32 baud)
{
float64 vclk = 110.000 * 1000000.0;
uint32 f = ((sci->GCR1 & 2U) == 2U) ? 16U : 1U;
uint32 temp;
float64 temp2;

temp = (f*(baud));
temp2 = ((vclk)/((float64)temp))-1U;
temp2 = floor(temp2 + 0.5);
sci->BRS = (uint32)((uint32)temp2 & 0x00FFFFFFU);

}

And I try another method
void sciSetBaudrate(sciBASE_t *sci, uint32 baud)
{
/** - set baudrate */
scilinREG->BRS = 1431; /* pre-scale 1431 = 4800 pbs*/
}

But the same can't receive by baud rate set to 4800

thanks