UART 115200 with x3 sampling
Javalin
Posts: 892
All,
Happy new year!!
Quick ISR question;· If I want to run an ISR dual uart using 3 times sampling rather than 4 so I can add buffer code to the ISR, would the following figures be correct?
SX18 at 50mhz (1/50000000 = 20ns)
int_period at 144 (144 * 20ns = 2.88us)
baud_rate_divisor at 3 (3 * 144 = 4.32us)
baud_rate_start_delay at 4 (4 * 144 = 5.76us - a little short I know)
So with a dual uart approach I guess every 3 ISR's I am transmitting and recieving (bar start bits) on one of the uarts.
Does this look correct?
Many thanks for any help!!
James
Happy new year!!
Quick ISR question;· If I want to run an ISR dual uart using 3 times sampling rather than 4 so I can add buffer code to the ISR, would the following figures be correct?
SX18 at 50mhz (1/50000000 = 20ns)
int_period at 144 (144 * 20ns = 2.88us)
baud_rate_divisor at 3 (3 * 144 = 4.32us)
baud_rate_start_delay at 4 (4 * 144 = 5.76us - a little short I know)
So with a dual uart approach I guess every 3 ISR's I am transmitting and recieving (bar start bits) on one of the uarts.
Does this look correct?
Many thanks for any help!!
James
Comments
FYI - Because I am alternatly sampling two uarts alternate uarts are sampled at 2.88us. So each uart is sampled at 5.76us. So I completely miss the sampling in a divisable 8.68us (1/115200) timebase.
Doh.