Delay between uart bytes happens when UP_RX is connected.

[Anonymous]

I'm working on WICED SMART SDK 2.0.1.

I try to send several bytes through UART which baud rate is 19200.

but there is delay between first byte and second byte about 2msec when I enabled message trace by SW2 ON.

With SW2 Off, no delay.

Can anybody help this issue?

[MichaelF_56 · Accepted solution]

I don't think the FTDI device is doing any type of buffering when SW2 is on, but the firmware may be a bit confused when RX is high when in app mode (because SW2 is turned on).

When sampled on RESET only:

HCI UART Rx = High (Programming mode)
HCI UART Rx = Low (Application mode)