UDOO BOLT features two pinout headers (dual-row 40 Pins), one on the top(CN24) and another on the bottom(CN25) of the board.

  • CN24 - Top: The pin header connector on the top of the board is connected to the ATmega32U4 microcontroller (Arduino® Leonardo-compatible). Check the Arduino Leonardo-compatible(ATmega32U4) Pinout section to know how to use it through the Arduino® programming.
  • CN25 - Bottom: The pin header connector on the bottom of the board is connected to the Embedded Controller(MEC1705). The EC is used to manage some functionalities of the board like the fan management, the wake up of the Ryzen™ processor and others. The EC also manages the exposed buses in the CN25 pinout header like UART, I2C, etc. and these are usable from the main AMD Ryzen™ processor.

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Since the Arduino Pinout connector (CN24) is fully described in the dedicated section, we describe only the pinout header of the EC (CN25) in this page.


Embedded Controller I/O Pin header - CN25

The Embedded Controller input/output (I/O) pins operate at 3.3V.

Pinmuxing

The image below shows the list of all possible functions assigned to each Pin.

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Here you can find the Embedded Controller [Microchip MEC1705 datasheet](http://ww1.microchip.com/downloads/en/DeviceDoc/MEC170x-Data-Sheet-DS00002206D.pdf).

UART 0 and UART 1

Universal Asynchronous Receiver/Transmitter (UART) provides serial communication capability with external devices.

The UART 0 is available at Pins 34, 36, 38, 40.
The UART 1 is available at Pins 33, 35, 37, 39.

UART 0

Pin Function EC PAD
34 UART0_RX UART0_RX
36 UART0_TX UART0_TX
38 UART0_RTS UART0_RTS#
40 UART0_CTS UART0_CTS#

UART 1

Pin Function EC PAD
33 UART1_RX UART1_RX
35 UART1_TX UART1_TX
37 UART1_RTS UART1_RTS#
39 UART1_CTS UART1_CTS#

Accordingly to the Microchip MEC1705 datasheet these are full-function Serial Port that supports the standard RS-232 Interface. The baud rate goes from 50 to 3000000.

The UARTs are directly propagated to the OS as Legacy UART so you can already interact with they.

UARTs on Linux

On Linux the UARTs are seen as standard tty devices. The addresses are set by default to 0x3f8 and 0x2f8.

You should find the UARTs available on the devices /dev/ttyS0 and /dev/ttyS1 on Ubuntu with a baudrate of 115200.
The device name assigned by the Linux Distro you are using can change, you can check the name assigned running the command:

dmesg | grep tty

UARTs on Windows 10

On Windows the UARTs are seen as standard COM devices. The addresses are set by default to 0x3f8 and 0x2f8.

You should find the UARTs available on the devices COM1 and COM2 on Windows 10.

I2C 1 and I2C 2

The I2C (Inter-IC) bus is a bi-directional, two-wire serial bus that provides a communication link between integrated circuits (ICs). Phillips introduced the I2C bus 20 years ago for mass-produced items such as televisions, VCRs, and audio equipment. Today, I2C is the de-facto solution for embedded applications.

The I2C 1 is available at Pins 8, 10.
The I2C 2 is available at Pins 7, 9.

I2C 1

Pin Function EC PAD
8 I2C1_SCL I2C08_SCL
10 I2C1_SDA I2C08_SDA

I2C 2

Pin Function EC PAD
7 I2C2_SCL I2C09_SCL
9 I2C2_SDA I2C09_SCL

Check the Microchip MEC1705 datasheet for more info about the I2C interface.

SPI

The Serial Peripheral Interface (SPI) is a synchronous serial communication interface specification used for short-distance communication, primarily in embedded systems.
The SPI may be accurately described as a synchronous serial interface, but it is different from the Synchronous Serial Interface (SSI) protocol, which is also a four-wire synchronous serial communication protocol.

The SPI is available at Pins 1, 2, 3, 4.

Pin Function EC PAD
1 SPI_MISO SPI0_MISO
2 SPI_CS# SPI0_CS#
3 SPI_MOSI SPI0_MOSI
4 SPI_CLK SPI0_CLK

Fan Controller

You can control an external Fan using the Fan Controller Pins.

The Fan controller is available at Pins 11, 12.

Pin Function EC PAD
11 FANOUT0 PWM0
12 FANTACH0 FAN_TACH0

The Fan Out is used as a PWM output to control the Fan Speed. The Fan Tachometer is used as in Input to capture the Fan Speed.
Remember you also need to provide the Voltage and Ground Pins to the external Fan.

These two signals (out and tachometer) are only 3.3V digital pins exposed by the controller and therefore do not deliver power.
To drive a 3-pin fan you need a power circuit that gives the right voltage to the fan. For example, this is the circuit used to drive the 5V fan installed above the heatsink:

fan circuit

Wake Pins

The Wake pin can be used as an interrupt, the signal is caught by the EC and propagated to wake up the main AMD Ryzen™ processor from S3/S4/S5 status.

The Wake is available at Pin 6.

Pin Function EC PAD
6 WAKE# GPIO025

Keyboard Scan

The Keyboard Scan Interface block provides a register interface to the EC to directly scan an external keyboard matrix of size up to 11x5.

  • KS Input [4:0] : Column inputs from external keyboard matrix.
  • KS Output[10:0]: Row outputs to external keyboard matrix.

The Keyboard Scan is available at Pins from 13 to 28.

Pin Function EC PAD
13 KSO0 KSO00
14 KSI0 KSI0
15 KSO1 KSO01
16 KSI1 KSI1
17 KSO2 KSO02
18 KSI2 KSI2
19 KSO3 KSO03
20 KSI3 KSI3
21 KSO4 KSO04
22 KSI4 KSI4
23 KSO8 KSO08
24 KS11 KSO11
25 KSO9 KSO09
26 KSO12 KSO12
27 KSO10 KSO10
28 KSO13 KSO13
This page was last updated on Thursday, September 12, 2019 at 3:01 AM.