Config baud rate at Run time on the Thingy91

[Adeel]

Hi Dev team,

I am working with the Thingy91 and I have connected it to an external sensor through UART-1. 

I am connecting another sensor through the same UART but with a different baud rate. In order to make them both running through the same UART, I need to be able to configure the baud rate at run time. 

Could you let me know how this could be done ? 

Right now, I have my config as : thingy91_nrf9160ns.overlay file.

&uart1 {
	current-speed = <9600>; 
	status = "okay";
	tx-pin = <13>;
	rx-pin = <16>;
	rts-pin = <14>;
	//cts-pin = <05>;	
};

The current baud rate is 9600 , but I would like it to switch between 9600 and 1200 at run time.

Regards,

Adeel.

[Carl Richard]

Hi, Adeel!

This should be no problem! I've attached a simple demonstration below that updates the baudrate to 9600. Notice how the peripheral must be disabled properly before the register can be updated.

 

NRF_UARTE1->ENABLE = UARTE_ENABLE_ENABLE_Disabled;
NRF_UARTE1->EVENTS_RXTO = 0; 
NRF_UARTE1->TASKS_STOPRX =1; 

while (NRF_UARTE1->EVENTS_RXTO == 0); // Wait for RXTO 
/* Do you stuff here*/
NRF_UARTE1->BAUDRATE = (UARTE_BAUDRATE_BAUDRATE_Baud9600 << UARTE_BAUDRATE_BAUDRATE_Pos);
printk("Value of baudrate register : %d \n",NRF_UARTE1->BAUDRATE);

NRF_UARTE1->ENABLE = UARTE_ENABLE_ENABLE_Enabled;

Best regards,
Carl Richard

[Adeel]

Hi Carl,

Thanks for the explanation. While I understood most of the part, I couldn't clearly get what Line 7 of the code does.

Does it change the baud rate from what is assigned initially in the overlay file to 9600 ? For my requirement, I need the baud rate to keep changing from 1200 to 9600 and to keep repeating this as and when I call the different sensors.

Regards,

Adeel.

[Carl Richard]

Hi, Adeel!

My pleasure. I was maybe unclear; the code I shared earlier is what you must do each time you change the baudrate. I demonstrated for 9600, but if you want to change to 1200 the line is as follows:

NRF_UARTE1->BAUDRATE = (UARTE_BAUDRATE_BAUDRATE_Baud1200 << UARTE_BAUDRATE_BAUDRATE_Pos);

Best regards,
Carl Richard

[Adeel]

Hi Carl,

Thanks a lot for clearing things up :). I understood how its done now.

Regards,

Adeel.

[Carl Richard]

Good to hear, Adeel!

Best regards,
Carl Richard

[Adeel]

Hi Carl,

Not sure if this is a closed ticket, but I was facing issues while trying out the above configuration for uart_1 on Thingy91. 

I have a sensor running at 9600 baud and another at 1200 baud. When I manually configure the baud rates in the overlay file (1200 once and 9600 next time), the data is received perfectly when I work around with the sensors individually. 

However, now I tried to configure baud rate in runtime through the above config as I needed both sensors data simultaneously. The overlay config is set to 9600, so by default, I get my first sensor data which is at 9600 baud. But when I set the baud rate to 1200 using the above config in my code, the baud rate does set to 1200 as I see in the printk() but I dont receive any data from my sensor that works on 1200 baud. Not sure what could be the issue here as I was expecting my data to be received when the baud rate changed. Is there any additional thing to be done other than this ?

Regards,

Adeel.