5.3.8 UEXT1
The 10-pin UEXT connectors are typically mounted on Olimex boards. They pack three common
interfaces in a single connector – UART, I2C and SPI. You can use the UEXT connector to access
this interfaces easier (via jumper wires, for example).
You can also connect expansion modules to the UEXT connectors. More on UEXT might be found
here:
https://www.olimex.com/Products/Modules/UEXT/
Pin #
Signal name
1
3.3 V
2
GND
3
TXD1
4
RXD1
5
SCL1
6
SDA1
7
MISO1
8
MOSI1
9
SCK1
10
UEXT1_CS
5.3.9 UEXT2
UEXT2 features other UART, I2C and SPI signals. However there is multiplexing on some of the
lines which might cause problems if you are trying to use the line on both places.
The I2C data lines (SCL2, SDA2) are used for the built-in the board accelerometer. The SPI clock
signal AC1TX/SCK3A is used by the SD card connector.
Pin #
Signal name
1
3.3 V
2
GND
3
U2TX
4
U2RX
5
SCL2
6
SDA2
7
MISO3A
8
MOSI3A
9
AC1TX/SCK3A
10
UEXT2_CS
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