Using Multiple LPUARTS in different Ports

[CEPL_Dev]

Microcontroller - NXP Kinetis MKE14F512VLL16

IDE - MCUXpresso v11.3.0

SDK - SDK_2.x_MKE14F512XXX16 ,v2.8.8

Hello,

I've an application in which I have to use the same LPUART module in two different ports. Different peripheral is connected to each port and I don't want to use them simultaneously.

Peripheral 1(P1) is connected to:

PTA3 (ALT6)- LPUART0-TX

PTA2 (ALT6)- LPUART0-RX

Peripheral 2(P2) is connected to:

PTB0 (ALT2)- LPUART0-RX

PTB1 (ALT2)- LPUART0-TX

In my application, I'm initializing the LPUART0 module with Port A2 and A3 using the following code.

void InitLPUART0(void){
PCC->CLKCFG[PCC_LPUART0_INDEX] |= PCC_CLKCFG_PCS(3); //System Oscillator Bus Clock
PCC->CLKCFG[PCC_LPUART0_INDEX] |= PCC_CLKCFG_CGC(1); //PCC Configuration - Enable Clock

PORTA->PCR[2] |= PORT_PCR_MUX(6); /* LPUART - ALT6 */
PORTA->PCR[3] |= PORT_PCR_MUX(6);

LPUART0->CTRL &= ~(LPUART_CTRL_TE_MASK | LPUART_CTRL_RE_MASK);
LPUART0->BAUD = BAUD_115200; //48M/(26*16)Baud rate for 115200bps

LPUART0->CTRL |= LPUART_CTRL_RIE(1); /* Receiver Interrupt Enable */
LPUART0->CTRL |= LPUART_CTRL_TE(1); /* Transmitter enable */
LPUART0->CTRL |= LPUART_CTRL_RE(1); /* Receiver Enable */

NVIC_EnableIRQ(LPUART0_RX_IRQn); 
}

Initially ,this is working as expected. The system is sending data as expected through the port.

When I need to use the other peripheral, I'm shifting the LPUART0 to the other port as shown below.

LPUART0->CTRL &= ~(LPUART_CTRL_TE_MASK | LPUART_CTRL_RE_MASK); /* Disable Tranceiver */

PORTA->PCR[3] |= PORT_PCR_MUX(1); /* LPUART - ALT1 - GPIO */
PORTA->PCR[2] |= PORT_PCR_MUX(1);

PORTB->PCR[0] |= PORT_PCR_MUX(2); /* LPUART - ALT2 - UART */
PORTB->PCR[1] |= PORT_PCR_MUX(2);

LPUART0->CTRL |= (LPUART_CTRL_TE_MASK | LPUART_CTRL_RE_MASK); /* Enable Tranceiver */

After shifting the system is supposed to send the data through the Port B to peripheral 2. But the LPUART lines are idle even though the transmission code is running. After switching ports, if I switch back to peripheral 1 in Port A using the same method, it doesn't respond either.

The system is working if use either of the ports without switching to the another.

What is wrong in this method?

[CEPL_Dev · Accepted solution]

Hello all,

Just found out the solution. I was overwriting bits 8, 9 and 10 corresponding to the MUX settings in the PORTx_PCR register instead of clearing them. 

Corrected method is posted below.

void SelectCOMPort(COMPORT_TYPE CPort){ /* Directs LPUART0 to the required port and disables others */
	LPUART0->CTRL &= ~(LPUART_CTRL_TE_MASK | LPUART_CTRL_RE_MASK);	/* Disable Tranceiver */
	switch (CPort)
	{
	case PORT_1:
		PORTB->PCR[0] &= ~(BIT8 | BIT9 | BIT10); 	/* LPUART - Disable */
		PORTB->PCR[1] &= ~(BIT8 | BIT9 | BIT10);

		PORTA->PCR[3] |= PORT_PCR_MUX(6); 			/* LPUART - ALT6 - to UART */
		PORTA->PCR[2] |= PORT_PCR_MUX(6);

		break;
	case PORT_2:
		PORTA->PCR[3] &= ~(BIT8 | BIT9 | BIT10);  	/* LPUART - Disable */
		PORTA->PCR[2] &= ~(BIT8 | BIT9 | BIT10);

		PORTB->PCR[0] |= PORT_PCR_MUX(2); 			/* LPUART - ALT2 - to UART */
		PORTB->PCR[1] |= PORT_PCR_MUX(2);
		break;
	default:
		break;
	}
	LPUART0->CTRL |= (LPUART_CTRL_TE_MASK | LPUART_CTRL_RE_MASK);	/* Enable Tranceiver */
}