Posts: 4
Registered: ‎02-09-2015

SI4461 first byte timing error

I use two SI4461, the first configured as direct TX and the second as Direct RX.
I use the UART for send the commands from the first to the second SI4461 and the UART configuration is
19200 bps
1 start bit
8 data bit
1 parity bit
1 stop bit

The commands rate is about 1-2 per second, and commands have a length of 36 bytes.

I have a little problem with the first received byte.
Sometimes the bits length of the first received byte is wrong, the bit length is about 50us (or a little bit less) instead of 52 and after 11 bit i have a frame length of about 549-550 us instead of 573-574us.

The difference of 23 - 24 us brings the mcu to miss the stop bit because the frame length (or bits length )is out of the MCU bitrate tolerance.

This behavior happens sometimes after 100-200 commands and sometimes after few commands (5-25 commands).

The second SI4461 has this configuration

Modulation Type : 2FSK
Data Rate : 19.2
Deviation : 75 kHz
RX Bandwidth : Auto-Cal
RX Data Error Rate : tried both 0%-1% and 1%-10%

Can someone give me some information on this behavior and if its possible to correct it.