Olimex Support Forum

OLinuXino Android / Linux boards and System On Modules => A20 => Topic started by: kaloyan on September 02, 2014, 02:12:47 PM

Title: UART0 RX0 doesn't work
Post by: kaloyan on September 02, 2014, 02:12:47 PM
Hello,
I use a USB-TTL PL2303HX converter for serial console on A20-Olinuxino-LIME-4G, rev. C

The UART RX0 pin is not working.
I have tested the converter RX/TX lines and their leds light up, only on the board TX pin.

Anyone having a simillar issue ?
Title: Re: UART0 RX0 doesn't work
Post by: JohnS on September 02, 2014, 02:17:34 PM
How exactly have you connected it?  How many pins & which?

Did you try looping its Tx to Rx?

John
Title: Re: UART0 RX0 doesn't work
Post by: kaloyan on September 02, 2014, 02:23:41 PM
I just found a thread saying PL2303 gives 5V output on the TX/RX lines.
I hope i didn't kill my board.


Title: Re: UART0 RX0 doesn't work
Post by: kaloyan on September 03, 2014, 01:02:43 AM
Is the USB serial calbe F, from olimex, based on the PL2303HX chip ?
This is the one I have
(http://yupi.bg/pl2303hx.jpg)
Title: Re: UART0 RX0 doesn't work
Post by: dave-at-axon on September 03, 2014, 12:44:38 PM
Quote from: kaloyan on September 02, 2014, 02:23:41 PM
I just found a thread saying PL2303 gives 5V output on the TX/RX lines.
I hope i didn't kill my board.

If you connected the TX at 5V to the Olimex board with 3.3V input level and not 5V tolerant, then you may well have done damage.
Title: Re: UART0 RX0 doesn't work
Post by: kaloyan on September 04, 2014, 10:31:40 AM
I have measured my serial module, and it works at 3.3V.
Which means my board UART0 port is damaged (my own fault).

Anyone knows how to check what is damaged ?
Title: Re: UART0 RX0 doesn't work
Post by: tandr on September 19, 2014, 03:22:05 PM
I have the same problem. My cable does work with other boards wich are at voltage level 3.3V.
Tested 3 different boards of the A20-SOM (Revision B).


Can anyone check this?
BTW: TX works great