TMS320F28375S: SCI- Communication is not happening in Custom Board(F28375S )

Hi Ajay,

When you say "custom board" did you design it yourself and modeled it after the F28377S? If so, there might be something in hardware going on preventing you from establishing the communication. I would double check with the LAUNCHXL_F28377S schematic and make sure everything is correct there.

If you run the 'sci_ex2_loopback_interrupts" example does that work for you? This is using internal loopback mode so its a good way to make sure your SCI module is still functional.

Also, when you run "sci_ex3_echoback" example" what do you see when you open up a terminal window?

Best Regards,

Marlyn

Dear Marlyn,

 we checking with respect to  reply,    please find our custom board circuit below , we directly connected F28375S  SCI_B pins to jumper pin(JP_12 and JP13) and we checking loopback program not working..... so We tried LED on / off GPIO 70 and 71.. its working..

but with respect to last reply sci example loop back  program which we are attached is not working..

Kindly guide us project setting

 Regards

Rani

Hi Rani,

When you tried the sci_ex2_loopback_interrupts' example did you modify anything in the code? Does it just result in a data mismatch error or how do you know it does not work?

Looking at the configuration code you attached a bit closer I see that you configured the SCI pins below,

 GPIO_setPinConfig(DEVICE_GPIO_CFG_SCIRXDA);  
 GPIO_setPinConfig(DEVICE_GPIO_CFG_SCITXDA);

DEVICE_GPIO_CFG_SCIRXDA actually maps to 'GPIO_28_SCIRXDA' and DEVICE_GPIO_CFG_SCITXDA maps to 'GPIO_29_SCITXDA'. 

Instead can you please try to set the pin configuration in the following way,

GPIO_setPinConfig(GPIO_71_SCIRXDB)
GPIO_setPinConfig(GPIO_70_SCITXDB)

Best Regards,

Marlyn

Marlyn,

Marlyn Rosales Castaneda20 said:

When you tried the sci_ex2_loopback_interrupts' example did you modify anything in the code? Does it just result in a data mismatch error or how do you know it does not work?

  Now loop back is working fine . When I am communicate with external device getting "framing error" in logic analyzer .

 We are using Oscillator as 20Mhz for that changed in device .h file

Then I have added in _LAUNCHXl_F28377S in predefined symbol. but we using TMS320F28375S for our custom board ... any configuration require for 176pin..

 How to set low speed clock pre scalar value properly?

one more doubt , Without using external crystal oscillator can do communication process (Example using System clock(200mhz))?

how to configure the using only system clock  for communication Process?

 I think so Frequency mismatching is happen . I couldn't find out can you help me to sort out this problem.

Thanks & Regards,

Rani

Hi Rani,

I see on the screenshot you attached that you changed DEVICE_OSCSRC_FREQ to have a frequency of 20000000U,

However, DEVICE_SYSCLK_FREQ is still defined as ((DEVICE_OSCSRC_FREQ * 40 * 1) / 2) which will give you 400MHz,

You need the following configuration for your 20MHz oscillator:

//
// 20MHz XTAL. For use with SysCtl_getClock().
//
#define DEVICE_OSCSRC_FREQ          20000000U

//
// Define to pass to SysCtl_setClock(). Will configure the clock as follows:
// PLLSYSCLK = 20MHz (XTAL_OSC) * 20 (IMULT) * 1 (FMULT) / 2 (PLLCLK_BY_2)
//
#define DEVICE_SETCLOCK_CFG         (SYSCTL_OSCSRC_XTAL | SYSCTL_IMULT(20) |  \
                                     SYSCTL_FMULT_NONE | SYSCTL_SYSDIV(2) |   \
                                     SYSCTL_PLL_ENABLE)

//
// 200MHz SYSCLK frequency based on the above DEVICE_SETCLOCK_CFG. Update the
// code below if a different clock configuration is used!
//
#define DEVICE_SYSCLK_FREQ          ((DEVICE_OSCSRC_FREQ * 20 * 1) / 2)

The above configuration is actually the default one if you do not define _LAUNCHXL_F28377S. Try setting the above configuration and see if that works.

Ajay S said:

 How to set low speed clock pre scalar value properly?

In your main() function within the sample projects there is a 'Device_init()' function. Within that function you can change your low speed clock prescalar

    //
    // Make sure the LSPCLK divider is set to the default (divide by 4)
    //
    SysCtl_setLowSpeedClock(SYSCTL_LSPCLK_PRESCALE_4);

Ajay S said:

Without using external crystal oscillator can do communication process (Example using System clock(200mhz))?

Yes, you can choose your clk source through the CLKSRCCTL1 register. For example, the code above chose 'SYSCTL_OSCSRC_XTAL' but there are other options such as 'SYSCTL_OSCSRC_OSC1', check in sysctl.h

Best Regards,

Marlyn

Marlyn,

Marlyn Rosales Castaneda20 said:

Yes, you can choose your clk source through the CLKSRCCTL1 register. For example, the code above chose 'SYSCTL_OSCSRC_XTAL' but there are other options such as 'SYSCTL_OSCSRC_OSC1', check in sysctl.h

Instead of SYSCTL_OSCSRC_OSC1 used  SYSCTL_OSCSRC_OSC2  . For SCI communication can I use OSC2?

#define DEVICE_SETCLOCK_CFG         (SYSCTL_OSCSRC_OSC2  | SYSCTL_IMULT(38) |  \
                                    SYSCTL_FMULT_3_4 | SYSCTL_SYSDIV(2) |   \
                                     SYSCTL_PLL_ENABLE)
  

Thanks & Regards,

Rani

Rani,

Ajay S said:

Instead of SYSCTL_OSCSRC_OSC1 used  SYSCTL_OSCSRC_OSC2  . For SCI communication can I use OSC2?

You may, but note that this is not just setting the frequency that will go through the LSP divider and eventually be the LSPCLK for the SCI, it is setting up SYSCLK for your device. Please take a look at the diagram below.

Did you try the configuration I showed in my last reply?

Best Regards,

Marlyn

Marlyn,

Marlyn Rosales Castaneda20 said:

Did you try the configuration I showed in my last reply?

  Yes ,tried but it doesn't work.

Marlyn Rosales Castaneda20 said:

but note that this is not just setting the frequency that will go through the LSP divider and eventually be the LSPCLK for the SCI, it is setting up SYSCLK for your device. Please take a look at the diagram below.

I not am sure my understanding is correct ... OSC1, OSC2 ,XTAL everything works same in setting up SYSCLK,LSPCLK from this diagram .

It may varies in application wise given in the table ...

I have configured OSC2 with reference to TRM.

#define DEVICE_SETCLOCK_CFG         (SYSCTL_OSCSRC_OSC2  | SYSCTL_IMULT(38) |  \
                                    SYSCTL_FMULT_3_4 | SYSCTL_SYSDIV(2) |   \
                                     SYSCTL_PLL_ENABLE)

How to configure OSC1?  (SYSCTL_IMULT,  SYSCTL_FMULT_3_4).

Thanks & Regards,

Rani

Hi Rani,

Ajay S said:

Yes ,tried but it doesn't work.

Are you still getting the framing error? Would it be possible to check what your baud rate is through an oscilloscope?

Ajay S said:

How to configure OSC1?  (SYSCTL_IMULT,  SYSCTL_FMULT_3_4).

You have configured OSC2 correctly based on what you provided. To configure OSC1 it would be the same configuration (they are both 10MHz), just swap 'SYSCTL_OSCSRC_OSC2' for 'SYSCTL_OSCSRC_OSC1'.

Best Regards,

Marlyn

Marlyn,

Marlyn Rosales Castaneda20 said:

You have configured OSC2 correctly based on what you provided. To configure OSC1 it would be the same configuration (they are both 10MHz), just swap 'SYSCTL_OSCSRC_OSC2' for 'SYSCTL_OSCSRC_OSC1'.

  Thanks,OSC1 and OSC2 are working fine .

Marlyn Rosales Castaneda20 said:

Are you still getting the framing error? Would it be possible to check what your baud rate is through an oscilloscope?

 From controller to Logic analyzer Communication is works fine . If i am use OSC1 and OSC2 there is no problem at all.

But after RS485 module am getting wrong data ..

When I am work  same code  and  RS485 Module with Launchpad F28379D works fine ..

Only difference is Oscillator , in launchpad using XTAL  ,  custom board working with OSC1 / OSC2 ...

In launchpad F28379D if I am use OSC1/ OSC2 getting ESTOP error in device .c file , after force debugging (three times pressing the run button)code runs fine getting output at RS485 module side also .. Using XTAL  doesnt get this ESTOP error any more.

May oscillator affect this communication ? please suggest me to any mistake have done in choosing oscillator for communication process.

Can I go with OSC1/ OSC2 for communication( SCI) process to outside device  ?

Thanks & Regards,

Rani