UART1 on LCDK6748 not working

will Resnick

Other Parts Discussed in Thread: OMAP-L138, OMAPL138

Hi,

I purchased the LCDK6748 and I am trying to get the UART1 communication to work. I have my scope hooked to J15 pin 19. I set pin mux 4 to 0x22000000 which only enables the uart tx and recv. I don't care about cts and rts. After the pin mux I enable the psc for uart 1 using the psc enable function taken from the .gel file. I never see any level shift as I transmit data continuously. Is there a schematic error for the LCDK6748?

THanks,

Will

over 12 years ago

0 will Resnick over 12 years ago

Expert 2155 points

In the schematic, the Uart1 Tx and Recv lines are not connected to the J15 output connector. There are resistor pads that are not populated on the bottom of the board. 2 of those non-popped resistors is used for the Uart1. shorting the pads for the Tx and Recv and using 0 ohm resistors fixes the problem.

Will

0 German Chavarro over 10 years ago in reply to will Resnick

Prodigy 20 points

Hello Will,

I am practically facing the same issue and I'd like more information about physically where to connect Tx and Rx of UART1 module (LCDK6748). and how to configure it.

Regards,

Germán Ch.

0 mike hosek over 10 years ago in reply to German Chavarro

Prodigy 100 points

see OMAP-L138_C6748_LC_Dev_Kit_Ver_A6a-ckt-diagrams.pdf
TI OMAPL138 LCDK schematics - > focus.ti.com/download/freetools/omap-l138_c6748_lc_dev_kit_ver_a6a%20.zip

R208,R209 are below J16, pin 36
R205,R206 are below U26 (U26 is empty)
it looks like R208 is in and R209 R205 R206 are not.
I removed R208 and put in 100 ohms for R206. can now see what must be uart1_tx signal on J15,pin19

0 Senthilkumar Srinivasan over 10 years ago in reply to German Chavarro

TI__Mastermind 43660 points

Hello German Ch,

You need to remove R208 resistor and populate R206 & R209 to connect UART1 interface to the expansion connector J15.

Regards,
Senthil

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UART1 on LCDK6748 not working