topic Re: LPTMR0 stops working when using LPUART1? in Kinetis Microcontrollers

LPTMR0 stops working when using LPUART1?

ammarbazzaz — Wed, 16 Oct 2019 17:25:42 GMT

I am having trouble with the LPTMR0 when I use LPUART1 to transmit a small buffer of data (8 bytes). When I use LPUART0 everything works fine. The code structure is identical between the two (UART0 vs UART1), except for the modifications required to use one instance the LPUART peripheral vs the other. When I use UART1 the LPTMR0 stops generating interrupts after (or possibly during) the time that 8 bytes of data in the buffer are transmitted. More detail below.

MCU is an MKE16F512VLH16

The 30,000 ft view goes like this:

LPTMR0 is set up for a 1ms interrupt.

A flag is set in the LPTMR0 IRQ Handler that calls tick() which resides in main().

Inside tick() there is a static counter that counts to 1000 and then calls uart1_send().

Inside uart1_send() 8 bytes of data are sent (one by one) using the UART1_TX IRQ Handler.

Flags and the counters are cleared accordingly and this process repeats every 1000ms.

Using UART0 everything works fine.

Using UART1 the 8 bytes of data are transmitted once and then LPTMR0 IRQ Handler is never called again.

I am stomped, any assistance would be helpful. Relevant code snippets below:

void lpuart_iz (void) {

NVIC->ICPR[1] |= (1 << 0); // clear pending register for LPUART0 RX
NVIC->ISER[1] |= (1 << 0); // set enable register for LPUART0 RX

LPUART0->BAUD = 0xF00001A; // set SBR for 115,200 (115,385 actual), OSR for 16, 8.7us/bit, 87us/byte
LPUART0->CTRL |= 0xAC0000; // enable TX/RX interrupts, enable TX/RX

NVIC->ICPR[1] |= (1 << 2); // clear pending register for LPUART1 RX
NVIC->ISER[1] |= (1 << 2); // set enable register for LPUART1 RX

LPUART1->BAUD = 0xF00001A; // set SBR for 115,200 (115,385 actual), OSR for 16, 8.7us/bit, 87us/byte
LPUART1->CTRL |= 0xAC0000; // enable TX/RX interrupts, enable TX/RX

}

void lptmr_iz (void) {

NVIC->ICPR[1] |= (1 << 26); // clear pending register for LPTMR0
NVIC->ISER[1] |= (1 << 26); // set enable register for LPTMR0

   LPTMR0->CSR = 0x40; // timer mode, interrupts enabled, counter rests on match
   LPTMR0->CMR = LPTMR0_TICK; // 1ms period
   LPTMR0->CSR |= 0x01; // enable and start LPTMR0

if (!tick_flag) {tick_flag = 1;} // perform tick tasks immediately

}

int main(void) {

   clock_iz(); // initialize clocks and turn on peripheral gates
   port_iz(); // initialize ports and output states
   lpuart_iz(); // initialize lpuarts
   lptmr_iz(); // initialize and start lptrm0

while (1) {

if (tick_flag) tick(); // call tick tasks
if (uart_send_flag) uart1_send();

}

return 0;

}

void tick (void) { // tick tasks

static uint16_t supertick = 0;
static uint8_t state = 0;

if (supertick < 1000) supertick++;
else {

if (state) {RED_OFF; state = 0;}
else {RED_ON; state = 1;}

uart_send_flag = TRUE;
supertick = 0;

}

tick_flag = 0; // clear tick_flag for next call

}

void LPTMR0_IRQHandler (void) {

if (!tick_flag) {tick_flag = 1;}
LPTMR0->CSR |= 0x80; // clear interrupt flag

}

void uart1_send (void) {

static uint8_t i = 0;

if (i < UART_TX_BUFFER_SIZE) {

LPUART1->DATA = buffer[i];
i++;

NVIC->ICPR[1] |= (1 << 1); // clear pending register for LPUART1 TX
NVIC->ISER[1] |= (1 << 1); // set enable register for LPUART1 TX

}
else i = 0;

uart_send_flag = FALSE;

}

void LPUART1_TX_IRQHandler(void) {

NVIC->ICER[1] |= (1 << 1); // clear enable register for LPUART1 TX
uart_send_flag = TRUE;

}

Re: LPTMR0 stops working when using LPUART1?

Robin_Shen — Fri, 18 Oct 2019 07:27:26 GMT

Dear Ammar Bazzaz,

When you use LPUART0 everything works fine.
When you use LPUART1 instead of use LPUART0, LPTMR0 stops generating interrupts.
Have you debug the project?
I am afraid it was caused by the clock gate of LPUART1 is not enabled.
It will cause HardFault interrupt, during debug you should be able to observe it.

Best Regards,

Robin

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Re: LPTMR0 stops working when using LPUART1?

ammarbazzaz — Fri, 18 Oct 2019 15:07:55 GMT

Hi Robin,

Yes I use MCUExpresso IDE for debugging the project. There were no faults shown in the “Faults” TAB. Also the while(1) loop in main continues to run. Also, note that the LPUART1 port IS working. The problem is that the LPTMR0 stops. My clock_iz code is this:

void clock_iz (void) {

SCG->FIRCDIV = 0x101; // enable FIRCDIV1 & FIRCDIV2 to PCC, divide by 1 = 48MHz

PCC->CLKCFG[PCC_PORTA_INDEX] |= 0x40000000; // enable clock on PORT A

PCC->CLKCFG[PCC_PORTB_INDEX] |= 0x40000000; // enable clock on PORT B

PCC->CLKCFG[PCC_PORTC_INDEX] |= 0x40000000; // enable clock on PORT C

PCC->CLKCFG[PCC_PORTD_INDEX] |= 0x40000000; // enable clock on PORT D

PCC->CLKCFG[PCC_PORTE_INDEX] |= 0x40000000; // enable clock on PORT E

PCC->CLKCFG[PCC_LPUART0_INDEX] |= 0x43000000; // enable clock on LPUART0, peripheral clock source = FIRC_CLK

PCC->CLKCFG[PCC_LPUART1_INDEX] |= 0x43000000; // enable clock on LPUART1, peripheral clock source = FIRC_CLK

PCC->CLKCFG[PCC_LPTMR0_INDEX] |= 0x43000000; // enable clock on LPTMR0, peripheral clock source = FIRC_CLK

} // void clock_iz (void)

Does this information change your response? Thank you for your time to look at this.

Best Regards,

Ammar

Re: LPTMR0 stops working when using LPUART1?

Robin_Shen — Mon, 21 Oct 2019 09:07:36 GMT

Hi Ammar,

Please ensure the LPTMR0_PSR[PCS] configure the same clock source.

For example: LPTMR0_PSR[PCS] = 0

Best Regards,

Robin

Re: LPTMR0 stops working when using LPUART1?

ammarbazzaz — Mon, 21 Oct 2019 17:26:05 GMT

Hi Robin, Thank you for the response. Please note the following observations:

1) Everything works fine when using LPUART0

2) LPTMR0 works perfectly until sometime after the LPUART1_TX IRQ Handler is called

3) LPTMR0_PSR[PCS] is 00 out of reset and I do not change this in my code => maybe your code changes this somewhere?

Does this change your response?

Re: LPTMR0 stops working when using LPUART1?

Robin_Shen — Mon, 21 Oct 2019 22:22:11 GMT

Hi Ammar,

Would you please attach the whole project, it will help me check the issue faster.

Or you can send the project through case:00236277

Best Regards,

Robin

Re: LPTMR0 stops working when using LPUART1?

ammarbazzaz — Tue, 22 Oct 2019 16:49:45 GMT

Hi Robin,

I uploaded a cleaned up version of the project to CASE 00236277. Please let me know if you need anything else.

Thank you for your time on this!

Best Regards,

Ammar Bazzaz

President & Engineering Director

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