rolandvs/NUCLEO-F091RC_UART_CONNECTION.txt

## NUCLEO-F091RC_UART_CONNECTION.txt
# NUCLEO_STMF091RC
The NUCLEO boards have `ST-morpho` connectors and the `Arduino` connectors so anyone can hook up his/her favourite interfaces.

Please refer to document: [UM1724](https://www.st.com/content/ccc/resource/technical/document/user_manual/98/2e/fa/4b/e0/82/43/b7/DM00105823.pdf/files/DM00105823.pdf/jcr:content/translations/en.DM00105823.pdf)

## Arduino Serial Port
If one would like to use the Arduino connector to connect to a shield, you will run into trouble when the serial interface needs to be used.

The `NUCLEO_F091RC` PCB is not completely configured to work using the standard serial port; the `D0/D1` pins that refer to `PA3/PA2` for UART communication are simply **NOT** connected!

According to the manual (paragraph 6.8, page 25) you can remove the zero ohm resistors on the back to connect the UART2 to the pins `D0` or `PA3` and `D1` or `PA2`.

|Jumper | State | instruction                                    |
|-------|-------|------------------------------------------------|
|       |       | Default connects UART2 to VCOM port of ST-LINK |
| SB13  |  ON   | 0 Ohm/ solder joint                            |
| SB14  |  ON   | 0 Ohm/ solder joint                            |
| SB62  |  OFF  | open                                           |
| SB63  |  OFF  | open                                           |
|       |       | Connects UART2 to D0/D1 Arduino, VCOM not used |
| SB13  |  OFF  | open                                           |
| SB14  |  OFF  | open                                           |
| SB62  |  ON   | 0 Ohm / solder joint                           |
| SB63  |  ON   | 0 Ohm / solder joint                           |

When setting UART2 to use the D0/D1 the communication towards the VCOM is lost and as stated in the manual you can use two wires to make a connection between the VCOM and UART3 instead. However it requires to reroute another UART to the VCOM of the ST-LINK. Much simpler is run two cross wires from `CN7-1` to `CN10-35` and `CN7-2` to `CN10-37` to connect `UART3` instead and leave everything as it is. The patch can be made even simpler by running two wires on the back of the PCB from `CN7-1` to `CN10-36` and `CN7-2` to `CN10-38`. Then just install two jumpers between `CN10` `35-36` and `37-38`.
	# NUCLEO_STMF091RC
	The NUCLEO boards have `ST-morpho` connectors and the `Arduino` connectors so anyone can hook up his/her favourite interfaces.

	Please refer to document: [UM1724](https://www.st.com/content/ccc/resource/technical/document/user_manual/98/2e/fa/4b/e0/82/43/b7/DM00105823.pdf/files/DM00105823.pdf/jcr:content/translations/en.DM00105823.pdf)

	## Arduino Serial Port
	If one would like to use the Arduino connector to connect to a shield, you will run into trouble when the serial interface needs to be used.

	The `NUCLEO_F091RC` PCB is not completely configured to work using the standard serial port; the `D0/D1` pins that refer to `PA3/PA2` for UART communication are simply NOT connected!

	According to the manual (paragraph 6.8, page 25) you can remove the zero ohm resistors on the back to connect the UART2 to the pins `D0` or `PA3` and `D1` or `PA2`.

	\|Jumper \| State \| instruction \|
	\|-------\|-------\|------------------------------------------------\|
	\| \| \| Default connects UART2 to VCOM port of ST-LINK \|
	\| SB13 \| ON \| 0 Ohm/ solder joint \|
	\| SB14 \| ON \| 0 Ohm/ solder joint \|
	\| SB62 \| OFF \| open \|
	\| SB63 \| OFF \| open \|
	\| \| \| Connects UART2 to D0/D1 Arduino, VCOM not used \|
	\| SB13 \| OFF \| open \|
	\| SB14 \| OFF \| open \|
	\| SB62 \| ON \| 0 Ohm / solder joint \|
	\| SB63 \| ON \| 0 Ohm / solder joint \|

	When setting UART2 to use the D0/D1 the communication towards the VCOM is lost and as stated in the manual you can use two wires to make a connection between the VCOM and UART3 instead. However it requires to reroute another UART to the VCOM of the ST-LINK. Much simpler is run two cross wires from `CN7-1` to `CN10-35` and `CN7-2` to `CN10-37` to connect `UART3` instead and leave everything as it is. The patch can be made even simpler by running two wires on the back of the PCB from `CN7-1` to `CN10-36` and `CN7-2` to `CN10-38`. Then just install two jumpers between `CN10` `35-36` and `37-38`.