Henry Nguyen

Kinetis MK60 Uart Oversampling question

Discussion created by Henry Nguyen on Oct 4, 2017
Latest reply on Oct 4, 2017 by Henry Nguyen

hello,

 

i am using MK60 processor UART interface with a 24 Mhz OSC clock.  Our desired baud rate is 3.125 Mbps on RX and we also would like to reduce our power consumption by lowering the bus clock for uart.  However, looking carefully, the uart only allow a 16x oversampling.  The baud rate = UART clock / (16 * (SBR + BRFD).

 

My current UART clock is 60 Mhz, SBR = 1, and BRFA = 6 which convert this baud rate to 3.1578 Mbps which is ok.

however, if we want to lower the clock down to say below 50 Mhz like 30 or 40 Mhz to get a meaningful gain in power, it is impossible to set the baud rate to 3.1578 Mbps because the ratio of (SBR + BRDF) = 0.6.  I can not set SBR = 0 because the manual said that it would disable baud rate generator.  The closest option is 50 MHz which give me a combination of SRB+BRFD = 1.  

 

Other processor that we used in the past like Atmel Sam3x has the option to configure 8x or 16x oversampling when UART clock is slower. 

 

Does MK60 Kinetis have any option to oversample uart at lower rate like 8?  I searched the manual but can not find anything.

 

If MK60 does not have option to reduce the sampling rate, is there any possibility that i can configure 3.125 Mbps baud rate for UART clock less than 50 Mhz? 

 

Thanks,

Henry

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