How can we calculate the maximum speed of data transmission in RS-485 using K20D50M boards ?

[Amit_Kumar1]

Hello

I want to know that how do we calculate the maximum data transmission speed using k20D50 boards? Do we have any formula to calculate it?

Regards

Amit Kumar

[LuisCasado]

Hello,

Running the core/bus at 50 Mhz (K20D50) with 8Mhz crystal (TWR-FRDM) the maximum UART0, for example, baudrate is 3125000 bauds.

But that is not a practical value for RS485. You need to check the maximum speed allowed in tour RS-485 transceiver and you will need to check the capacitance in the line based on the length of the wires, number of devices connected, etc.

I think you will not have a limitation due to the K20, but due to the RS4-85 bus itself, transceiver, length of the bus and number of devices connected.

Luis

[Amit_Kumar1]

Thanks for the reply, I found out the formula for calculating baud rate is

I was wondering that can we increase the core clock by selecting the high external crystal oscillator value? How do we choose the external crystal and what is the maximum limit for external crystal which we can use in K20D50 uc?

thanks and regards,

Amit Kumar

[LuisCasado · Accepted solution]

Hi,

You wil use the PLL output clock, so changing the crystal value will not change anything. You are limited by the maximum clock possible in this part.

Luis