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Demo application hardware setup: UART2 PIC24FJ1024GB610 Explorer 16/32

Posted by tinchogleria on July 12, 2017

Hello! I've been trying to find "pin 2 and pin 3 of Explorer16 9way D socket" because I have to connect those pins for the example to work and I have been completely defeated. According to the MCU datasheet, UART2 is not mapped directly to specific pins, instead it is configurable to the available RPn / RPIn pins. So far all fantastic, but I can not find in the source code what this configuration is. I share the source code where the UART is configured, it is the file that I downloaded from freeRTOS.org. Could someone shed some light on this? I really appreciate the help of this forum. Thanks in advance.


Demo application hardware setup: UART2 PIC24FJ1024GB610 Explorer 16/32

Posted by rtel on July 12, 2017

This connection is on the connector - assuming the Explorer 16 hardware has not changed (it is an old demo) then you can just link the pins externally.

If you go to the webpage you link to there is a picture of our hardware set up at the top of the page. In the picture, on the bottom left corner you will see the power plug. Next to the power plug you will see the 9-way connector (the one you plug a serial cable into) mentioned in your quote. If you look very carefully at that 9 way connector in the photo, although barely visible, you will notice a little loop of wire (probably a paperclip of staple) sticking out of the connector - that is just pushed into the connector's pin 2 and pin 3 to connect them together.


Demo application hardware setup: UART2 PIC24FJ1024GB610 Explorer 16/32

Posted by tinchogleria on July 13, 2017

Thank you very much. Now I realize the reason why I didn't find it. The demo board has changed. The port24's web page (link in my previous message) has a broken link to the microchip site with the details of the demo board used then. I think the 9-way connector has been replaced by usb-serial connector. This is the demo board I'm using now: Explorer 16/32. (Click on the image at the right for zooming) Perhaps, should I try to re-map de UART2 pins? What would you do? Thanks again!


Demo application hardware setup: UART2 PIC24FJ1024GB610 Explorer 16/32

Posted by rtel on July 13, 2017

Probably easiest to just remove the comtest from the demo. The comtest was the part of the demo that was using the looped back uart (the bit of wire sticking out the 9-way connector).

To remove the comtest from the project you have to do two things.

1) Remove the line that creates the test tasks. That can be done in main.c by commenting out the line that calls vAltStartComTestTasks() or vStartComTestTasks().

2) Remove the line that checks to see if the comtest tasks are still running. That can be done by removing/commenting out the if() block that calls xAreComTestTasksStillRunning().


Demo application hardware setup: UART2 PIC24FJ1024GB610 Explorer 16/32

Posted by tinchogleria on July 13, 2017

I share you the function where the UART2 config happen, original from freeRTOS source code. I tried to follow the bits definition up to pic24fj1024gb610.h file, but honestly I can't figured it out. I assume this is a valid UART2 configuration, otherwise some error or warning should pop-up. Am I right? Where, in this function, is mapped UART2 pins?

~~~ xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength ) { char cChar;

/* Create the queues used by the com test task. */
xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

/* Setup the UART. */
U2MODEbits.BRGH		= serLOW_SPEED;
U2MODEbits.STSEL	= serONE_STOP_BIT;
U2MODEbits.PDSEL	= serEIGHT_DATA_BITS_NO_PARITY;
U2MODEbits.RXINV	= serNORMAL_IDLE_STATE;
U2MODEbits.ABAUD	= serAUTO_BAUD_OFF;
U2MODEbits.LPBACK	= serLOOPBACK_OFF;
U2MODEbits.WAKE		= serWAKE_UP_DISABLE;
U2MODEbits.UEN		= serNO_HARDWARE_FLOW_CONTROL;
U2MODEbits.IREN		= serNO_IRDA;
U2MODEbits.USIDL	= serCONTINUE_IN_IDLE_MODE;
U2MODEbits.UARTEN	= serUART_ENABLED;

U2BRG = (unsigned short)(( (float)configCPU_CLOCK_HZ / ( (float)16 * (float)ulWantedBaud ) ) - (float)0.5);

U2STAbits.URXISEL	= serINTERRUPT_ON_SINGLE_CHAR;
U2STAbits.UTXEN		= serTX_ENABLE;
U2STAbits.UTXINV	= serNORMAL_IDLE_STATE;
U2STAbits.UTXISEL0	= serINTERRUPT_ON_SINGLE_CHAR;
U2STAbits.UTXISEL1	= serINTERRUPT_ON_SINGLE_CHAR;

/* It is assumed that this function is called prior to the scheduler being
started.  Therefore interrupts must not be allowed to occur yet as they
may attempt to perform a context switch. */
portDISABLE_INTERRUPTS();

IFS1bits.U2RXIF = serCLEAR_FLAG;
IFS1bits.U2TXIF = serCLEAR_FLAG;
IPC7bits.U2RXIP = configKERNEL_INTERRUPT_PRIORITY;
IPC7bits.U2TXIP = configKERNEL_INTERRUPT_PRIORITY;
IEC1bits.U2TXIE = serINTERRUPT_ENABLE;
IEC1bits.U2RXIE = serINTERRUPT_ENABLE;

/* Clear the Rx buffer. */
while( U2STAbits.URXDA == serSET_FLAG )
{
	cChar = U2RXREG;
}

xTxHasEnded = pdTRUE;

return NULL;

} /-----------------------------------------------------------/ ~~~


Demo application hardware setup: UART2 PIC24FJ1024GB610 Explorer 16/32

Posted by tinchogleria on July 13, 2017

My last message should was posted before your last answer. Sorry for that, I didn't see your answer. I did the changes you suggested me. Effectively task #2 is not running now, but task #4 sometimes fail. I can not establish a period, but is frecuently. When everything is fine, I see "124ns max jitter" in my display. What could be causing this inconvenience?


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