Universal Asynchronous Receiver/Transmitter (UART) provides serial communication capability with external devices through a level converter and an RS-232 cable or through the use of external circuitry that converts infrared signals to electrical signals (for reception) or transforms electrical signals to signals that drive an infrared LED (for transmission) in order to provide low speed IrDA compatibility.

To see more detailed information look at the Chapter 65 on the iMX 6SoloX Reference Manual.

UDOO Neo UART ports

Table below gives a short description of the UART ports:

Name Function Description
UART_1 Cortex A9 serial debug On this serial it's possible to have access to a Linux console
UART_2 Cortex M4 MQX debug Freescale MQX real-time OS library uses this serial for debug info
UART_3 WL1831 Bluetooth chip Used to communicate with Bluetooth chip mounted on the board
UART_4 n.c. n.a.
UART_5 Arduino pin 0 /1 serial It can be used by M4 microcontroller through the Serial0 object
UART_6 Cortex A9 user serial Not enabled by default. It can be enabled on external A9 pinout

Debug UART ports

The serial debug ports (UART_1 and UART_2) are available on the external pinout. Signals can be accessed with a USB to TTL adapters.

UART 1

This UART is assigned to the A9 core as Debug Serial port. Over this serial it is possible to access a terminal console to login on a Linux shell. It can be accessed over the external pinout on the following pins:

PCB NAME SCHEMATICS SIGNAL NAME SCHEMATIC IMX6 PAD NAME REFERENCE MANUAL Pad Mux Register ALTERNATE
UART_1_TX 47 UART1_TXD GPIO_4 IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO04 ALT0 - UART1_TX_DATA
UART_1_RX 46 UART1_RXD GPIO_5 IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO05 ALT0 - UART1_RX_DATA

Default configuration

  • Baudrate: 115200
  • Data: 8 bit
  • Parity: none
  • Stop: 1 bit
  • Flow control: none
  • Kernel device name: /dev/ttymxc0

UART 2

This serial is controlled by the M4 core. This core runs code based on MQX real time OS/libraries. These are a set of libraries developed by Freescale. They can exploit at best the M4 architecture, avoiding a raw port of Arduino libraries. The UART_2 port is used for debug purposes. It can be accessed over the external pinout on the following pins:

PCB NAME SCHEMATICS SIGNAL NAME SCHEMATIC IMX6 PAD NAME REFERENCE MANUAL PAD NAME ALTERNATE
UART_2_TX 45 UART2_TXD GPIO_6 IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO06 ALT0 - UART2_TX_DATA
UART_2_RX 44 UART2_RXD GPIO_7 IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO07 ALT0 - UART2_RX_DATA

Default configuration

  • Baudrate: 115200
  • Data: 8 bit
  • Parity: none
  • Stop: 1 bit
  • Flow control: none
  • No kernel device (the kernel can't access this serial)

UART 3

This UART is connected to the Texas Instruments WL1831 chip for Bluetooh data communication purposes. It uses four signals at 1.8 Volts:

  • RX

  • TX

  • CTS

  • RTS

  • Kernel device name: /dev/ttymxc2

PCB NAME SCHEMATICS SIGNAL NAME SCHEMATIC IMX6 PAD NAME REFERENCE MANUAL PAD NAME ALTERNATE
UART_3_TX - BT_HCI_TX_1V8 SD3_DAT4 IOMUXC_SW_MUX_CTL_PAD_SD3_DATA4 ALT3 - UART3_RX_DATA
UART_3_RX - BT_HCI_RX_1V8 SD3_DAT5 IOMUXC_SW_MUX_CTL_PAD_SD3_DATA5 ALT3 - UART3_TX_DATA
UART_3_RTS - BT_HCI_RTS_1V8 SD3_DAT6 IOMUXC_SW_MUX_CTL_PAD_SD3_DATA6
UART_3_CTS - BT_HCI_CTS_1V8 SD3_DAT7 IOMUXC_SW_MUX_CTL_PAD_SD3_DATA7

* For these two signals the iMX 6Solox processor works in DCE mode.

UART 5

This is the serial controlled by the M4 core, available on the pins 0 and 1 on the external pinout. In the Arduino IDE you can access to this UART using the object Serial0.

Serial0.begin(115200); // Init the Serial at 115200 baudrate

Serial0.available(); // get the number of incoming bytes
Serial0.read(); // get the first byte in FIFO buffer

Serial0.write(); // write on output buffer byte array
Serial0.print(); // write on output buffer char array
Serial0.println(); // write on output buffer char array plus newline char

UART 6

This UART is user available, but it must be included in the device tree before the use. By default all of its pins are given to A9 in GPIO mode.

  • Kernel device name: /dev/ttymxc5
PCB NAME SCHEMATICS SIGNAL NAME SCHEMATIC IMX6 PAD NAME REFERENCE MANUAL PAD NAME ALTERNATE
UART_6_CTS_B 33 CSI0_DAT7 CSI0_DAT7 IOMUXC_SW_MUX_CTL_PAD_CSI_DATA07 ALT4 - UART6_CTS_B
UART_6_RTS_B 32 CSI0_DAT6 CSI0_DAT6 IOMUXC_SW_MUX_CTL_PAD_CSI_DATA06 ALT4 - UART6_RTS_B
UART_6_TX_DATA 31 CSI0_DAT5 CSI0_DAT5 IOMUXC_SW_MUX_CTL_PAD_CSI_DATA05 ALT4 - UART6_TX_DATA
UART_6_RX_DATA 30 CSI0_DAT4 CSI0_DAT4 IOMUXC_SW_MUX_CTL_PAD_CSI_DATA04 ALT4 - UART6_RX_DATA
UART_6_DCD_B 29 CSI0_DAT3 CSI0_DAT3 IOMUXC_SW_MUX_CTL_PAD_CSI_DATA03 ALT4 - UART6_DCD_B
UART_6_DTR_B 28 CSI0_DAT2 CSI0_DAT2 IOMUXC_SW_MUX_CTL_PAD_CSI_DATA02 ALT4 - UART6_DTR_B
UART_6_DSR_B 27 CSI0_DAT1 CSI0_DAT1 IOMUXC_SW_MUX_CTL_PAD_CSI_DATA01 ALT4 - UART6_DSR_B
UART_6_RI_B 26 CSI0_DAT0 CSI0_DAT0 IOMUXC_SW_MUX_CTL_PAD_CSI_DATA00 ALT4 - UART6_RI_B
This page was last updated on Friday, June 16, 2017 at 1:12 PM.