HummingBoard Pro/Base GPIOs
Description
[HB GPIO] GPIO, or General-Purpose Input/Output is a mechanism that allows a computing board to provide electrical contacts for signalling to a wide range of external devices. These pins allow commerical and hobbyist projects to do things like communicate with a “breakout board”, or individual physical modules – like a motor.
GPIO interfaces are different than other capabilities on a circuit board (like LVDS or the RTC integration) in that they provide a non-specific electrical interface. While these other interfaces have a set specification and set capability for an intended use (connecting to an LCD panel or a real-time clock, in the cited examples respectively) GPIO pins are used at the developer’s discretion. You could connect a motor. Or a temperature sensor. Or a lock solenoid. Or any one of millions of other device combinations for bringing information into the system – or sending information out from the HummingBoard device.
Pin header schematics
26 pin header
GPIO Header Pinout
Header Pin
Signal
Pad Name
GPIO Name
Linux GPIO Number (*)
J2 [pin 1]
3.3V
-
-
-
J2 [pin 2]
5V
-
-
-
J2 [pin 3]
I2C_SDA
EIM_D18
GPIO3_IO18
82
J2 [pin 4]
5V
-
-
-
J2 [pin 5]
I2C_SCL
EIM_D17
GPIO3_IO17
81
J2 [pin 6]
GND
-
-
-
J2 [pin 7]
GPIO 1
GPIO_1
GPIO1_IO01
1
J2 [pin 8]
UART TX
-
-
-
J2 [pin 9]
GND
-
-
-
J2 [pin 10]
UART RX
-
-
-
J2 [pin 11]
GPIO 73
EIM_DA9
GPIO3_IO09
73
J2 [pin 12]
GPIO 72
EIM_DA8
GPIO3_IO08
72
J2 [pin 13]
GPIO 71
EIM_DA7
GPIO3_IO07
71
J2 [pin 14]
GND
-
-
-
J2 [pin 15]
GPIO 70
EIM_DA6
GPIO3_IO06
70
J2 [pin 16]
GPIO 194
SD3_CMD
GPIO7_IO02
194
J2 [pin 17]
3.3V
-
-
-
J2 [pin 18]
GPIO 195
SD3_CLK
GPIO7_IO03
195
J2 [pin 19]
SPI_MOSI
EIM_CS1
GPIO2_IO24
56
J2 [pin 20]
GND
-
-
-
J2 [pin 21]
SPI_MISO
EIM_OE
GPIO2_IO25
57
J2 [pin 22]
GPIO 67
EIM_DA3
GPIO3_IO03
67
J2 [pin 23]
SPI_SCLK
EIM_CS0
GPIO2_IO23
55
J2 [pin 24]
ECSPI2_SS0
EIM_RW
GPIO2_IO26
58
J2 [pin 25]
GND
-
-
-
J2 [pin 26]
ECSPI2_SS1
EIM_LBA
GPIO2_IO27
59
Pins 16 and 18 are actually SD3_CMD and SD3_CLK signals that can be muxed to support flex can TX/RX interface (i.e. those can be connected to an external CAN). (*) SPI and I2C can also be muxed to be GPIO
Serial UART port access
The UART port for debug can be accessed on the 26 pin header as follows –
Pin 6/9/14/20/25 GND Pin 1 3.3V Pin 8 buffered i.MX6 UART TX – pulled up to 3.3v Pin 10 buffered i.MX6 UART RX – pulled up to 3.3v Notice that the pin number starts as pin #1 on the edge of the board, towards the micro-USB connector; then number #2 is the one towards the corner of the board. Accessing GPIO from Linux user space
General
Please have a look at WiringX, which also supports the Hummingboard:
Manual
The external GPIOs are available under the /sys/class/gpio folder in Linux.
To control on the GPIO pins you need to calculate the GPIO number XX (*) and run the commands below:
Get the current list of reserved GPIO
Reserve GPIO pin
Set GPIO pin Direction
Set the value of an output pin
Get the value of an input pin
Free GPIO pin
To calculate the GPIO number XX: XX = linux gpio number = (gpio_bank - 1) * 32 + gpio_bit
Example: To calculate the GPIO number of pin header J2 [pin 12] Pad Name GPIO3_IO08
GPIO Bank = 3, GPIO bit = 8
XX = (3 - 1) * 32 + 8 = 72
You can take the GPIO Number from the above table (*)
External Links and References
IMX6 Software Development/Drivers
IMX6 Som Documents
wiringHB
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