LAUNCHXL-CC2640R2: trying to read the UART

moshe jacobson18

Expert 2240 points

Part Number: LAUNCHXL-CC2640R2
Other Parts Discussed in Thread: CC2640R2F

Hi there

i'm trying to read the UART using the sample project uartEcho.

I'm using a RS232 to TTL adapter going into a RS232-USB adapter....this works fine with my MSP430 stuff.

The Uart_read() function does not return because nothing comes in to the port....the Tx side works fine.

I put a scope probe on Rx (DIO2)and noticed that the voltage went from 3.3V down to 2.6V which explains why the UART didn't see anything.
If i remove the RS232 adapter connection to DIO2 & place the probe on the adapter Rx pin i see the voltage going from 5V down to 0V which is as it should be.

This is happening on BOTH my launchpads.

Is there something i should be doing to ensure the launchpad pin draws the voltage down to below 2V so that the UART pin sees the RS232 signal??

thanks in advance

moshe

over 6 years ago

0 Fredrik K over 6 years ago

TI__Guru** 106705 points

Hi Moshe,

Have you remove the UART jumpers on the header block separating the debugger from the CC2640R2F?

The onboard XDS110 debugger also includes a UART port by the way, so you do not really need an external adapter.

Regards,
Fredrik

0 moshe jacobson18 over 6 years ago in reply to Fredrik K

Expert 2240 points

Thanks Fredrik

If ONLY all my problems were so easy to solve!!

I did see those jumpers but assumed it was for comms between the XDS itself & the CC....my very very bad assumption.

Yes, i vaguely knew there was a uart on the XDS as i saw it in the win10 device manager but assumed (again) it had something to do with debugging.

So now WHERE can i find all this info about using the uart?

The datasheet doesn't mention it & the schematics dont describe it....or have i missed something?

cheers

moshe

0 YiKai Chen over 6 years ago in reply to moshe jacobson18

Guru 735695 points

After you connect LaunchPad to your desktop, it will simulated two virtual COM ports, Application/User UART and Auxiliary Data Port. The Application/User UART COM port is connected to CC2640R2 UART TX/RX so you can open this COM port for communicating with CC2640R2.

0 moshe jacobson18 over 6 years ago in reply to YiKai Chen

Expert 2240 points

thanks Chen...i dont have an issue with using the comm port any more now that i know what it is...but i do still have an issue with where this information is written.

0 YiKai Chen over 6 years ago in reply to moshe jacobson18

Guru 735695 points

I am not aware that TI has document to describe this information.

0 Fredrik K over 6 years ago in reply to YiKai Chen

TI__Guru** 106705 points

Hi Moshe,

Good to hear that your problem was resolved!

If you go through SimpleLink Academy Project 0, you will see it used: http://dev.ti.com/tirex/explore/node?node=AJ7jWuST9RweXKhWHqlyWg__FUz-xrs__LATEST

Or Bluetooth Low Energy Fundamentals: http://dev.ti.com/tirex/explore/node?node=ADoEZBrWKWqhpyfpKc8WDw__krol.2c__LATEST

SimpleLink Academy is again linked from the Bluetooth Low Energy User´s Guide: http://dev.ti.com/tirex/explore/content/simplelink_cc2640r2_sdk_3_20_00_21/docs/blestack/ble_user_guide/html/ble-stack-3.x-guide/get-started.html#learn

I do agree though, that none of those links are sort of in your face if you are mostly reviewing the LaunchPad from a HW point of view, so perhaps we should add the information here as well: http://dev.ti.com/tirex/explore/node?node=AMtnAzoDezOokLAMkxUhag__FUz-xrs__LATEST

Regards,
Fredrik

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LAUNCHXL-CC2640R2: trying to read the UART