LPC 546 USART CONFIG USING REGISTER

[k_sunilgupta]

Hi all,

i want to do register level programing using LPC546 to interface usart, anyone could help me.

This is my configuration for usart0 in LPC546 for polling mode:-

USART0->CFG |= (1UL << 0); // USART ENABLE
USART0->BRG = 115200U; // SET BAUDRATE
USART0->CFG = 0x0U; // NO PARITY
USART0->CFG &=~ (1UL << 6); // 1 STOP BIT
USART0->CFG = 0x1U; // 8 BIT DATA LENGTH

USART0->CFG &=~ (1UL << 11); // ASYNC MODE
USART0->CFG &=~ (1UL << 12); // FALLING EDGE*/

But its not working, please suggest id anyone known this thing.

[k_sunilgupta]

i have checked all bits but not finding error from my side, 

[frank_m]

Did you think of enabling power and clock for the USART peripheral block ?

[k_sunilgupta]

I have POWER ON 

SYSCON->PDRUNCFG[0] |= (1 << 4)

AND I did not find clock for USART pheripheral block in user mannual, Please help me to creak this

[ZhangJennie]

If your USART is from FlexComm0, you need to make sure there is clock attaching to FlexComm0.

Please check USART demo code, CLOCK_AttachClk

[k_sunilgupta]

SYSCON->AHBCLKCTRL[1] |= (1UL << 11); // FLEXCOMM0 CLOCK ENABLE
SYSCON->FCLKSEL[0] = 0x4U;
SYSCON->FRGCTRL = 0x01;

void USART_0_INIT(void)
{

USART0->CFG |= (1 << 0); // USART ENABLE
USART0->BRG = 0x67; // SET BAUD RATE
USART0->CFG &=~ (1 << 6); // 1 STOP BIT
USART0->CFG |= (1 << 2); // 8 BIT MODE
USART0->FIFOCFG |= (1 << 16) | (1 << 0); // ENABLE TX
USART0->FIFOCFG |= (1 << 17) | (1 << 1); // ENABLE RX
USART0->CFG &=~ (1 << 11); // ASYNC MODE
USART0->CFG &=~ (1 << 12); // FALLING EDGE

}

[k_sunilgupta]

please check the code i have done the needful

[ZhangJennie]

Suggest you testing usart_polling SDK demo as a standard on the board. thus we can know if HW environment is ok.

If demo code works but your code can't,  make register comparison of demo and your code in debug code.

[k_sunilgupta]

have you ever config USART on register level programing ?

@ZhangJennie 

[k_sunilgupta]

please reply.

[ZhangJennie]

LPC546 only has SDK demo as official demo code. and I didn't test on other code.

If you don't use SDK, please follow the advice above, referring SDK usart demo, follow the usart initialization sequence and check the related register setting to config yours code.

[frank_m]

> have you ever config USART on register level programing ?

Easy solution.

Take the proposed SDK USART example, determine the sequence of initialisation steps either via static code analysis or debugging, and apply it to your code.

[k_sunilgupta]

i have done it now its working fine on register level.

[frank_m]

> i want to do register level programing using LPC546 to interface usart, anyone could help me.

Which is fine. But don't use magic numbers.

This forces others to read your code and the MCU manual in parallel, and crosscheck all your registers, bits, and shifts.

Many posters her like me are volunteers, and neither have the time nor the desire to do that.

Instead use the defines that come with the MCU-specific header in the SDK. For example, in LPC54628.h. That makes reading much easier.