mbed Serial on Nucleo UART4

[Andrew Neil]

Posted on August 13, 2015 at 01:14

I have already asked this question on the mbed site:

https://developer.mbed.org/questions/59656/Serial-What-are-the-Supported-pins/

It isn't clear from the Handbook whether this is even supposed to be supported. I tried instantiating as:

Serial uart4( PC_10, PC_11 );

But is seems that can't be sufficient, as USART3 can also use PC10 & PC11 - so how could it know?! #fail #nucleo #nucleo #uart #mbed #possibly-worst-forum-software #serial #keil #mbed

[Tesla DeLorean]

Posted on August 13, 2015 at 02:27

Well the ST-LINK VCP is definitely USART2 via PA2/PA3 on the

https://developer.mbed.org/platforms/ST-Nucleo-L152RE/

But somewhat irritatingly that conflicts with the D0/D1 of the header.

I'd have to wade through the manuals for USART3/UART4, but I could swear you'd have to manually modify the board to get those to the VCP TX/RX pins.

[Tesla DeLorean]

Posted on August 13, 2015 at 02:38

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM001058pdf

[Tesla DeLorean]

Posted on August 13, 2015 at 02:46

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/DM00098321.pdf

UART4 would also be viable on these pins, if you really needed to use USART3 somewhere else and in synchronous mode. With 64-pins I find that a tad improbable.

Not into mbed myself, but would suspect calling out the U(S)ART and specifying the pins to select as AF, should be enough for the magic inside the board/chip support code to get the chip set up properly, provided you'd dealt with the wiring externally. 

[Andrew Neil]

Posted on August 13, 2015 at 08:39

Sorry - I'm not talking about the 

 ST-LINK VCP  here at all.

I have serial comms with the PC over the 

ST-LINK VCP  working fine.

What I'm looking to do is to also have UART (or USART) comms on the header pins.

The UART4 pins seemed initially convenient - but any other pins would do.

I'm also not much into mbed (yet) - but the documentation on this does seem very skimpy (being kind).

:(

[Tesla DeLorean]

Posted on August 13, 2015 at 19:06

I've use PA9/PA10 USART1 before.

PA10 (D2) USART1-RX is usable for GPS shield.

The Morpho header has more opportunities.

[Andrew Neil]

Posted on August 14, 2015 at 23:47

Experimenting further, I can successfully printf() to UARTs 1 & 3; but printf() to UART 4 or 5 hangs.

#include ''mbed.h''
//------------------------------------
// Hyperterminal configuration
// 9600 bauds, 8-bit data, no parity
//------------------------------------
Serial pc(SERIAL_TX, SERIAL_RX);
//Serial uart1( PA_9, PA_10 );
Serial uart1( PB_6, PB_7 );
Serial uart3( PB_10, PB_11 );
Serial uart4( PC_10, PC_11 );
Serial uart5( PC_12, PD_2 );
DigitalOut myled(LED1);
int main() {
int i = 1;
pc.printf(''


Hello World !'');
while(1) { 
wait(1);
pc .printf(''

SERIAL_TX: %d.'', i);
//uart1.printf(''

UART1: %d.'', i);
//uart3.printf(''

UART3: %d.'', i);
uart4.printf(''

UART4: %d.'', i);
//uart5.printf(''

UART5: %d.'', i);
i++;
myled = !myled;
}
}

[Tesla DeLorean]

Posted on August 15, 2015 at 00:57

Yeah, I'd take a look at the board support code, and make sure it's enabling the right APB clocks for the USARTs

[Andrew Neil]

Posted on August 15, 2015 at 13:03

Yes.

The online compiler seems pretty useless in getting to see that, and exporting seems to be broken at the moment.

[Andrew Neil]

Posted on August 19, 2015 at 13:43

Thoroughly cheesed-off with mbed, Keil, and Nucleo at the moment!

:(

As noted, the debugging and browsing in the online compiler is pretty useless; so I thought I'd export to Keil.

But the mbed Export function is not working - everything is just stuck in the cloud.

:(

I eventually found a way to export something, but the Project does not build - and Keil's error message is unhelpful

http://www.keil.com/forum/60126

:(

I did finally get the project to build, only to find that it doesn't have the 

board support as source code anyhow - so useless for debugging this issue!!

:(

[Andrew Neil]

Posted on August 19, 2015 at 13:46

And, just to make me feel so much better, the stupid forum software decided to swallow my post, too!

:(