The Dragonwing IQ8-EVK contains one low-speed connector (JLS1) that provides access to various GPIOs, CAN, QUPs, and other interfaces.

Pinout

The figure below shows the default functions of the IQ-8275 EVK 40-pin LS connector.

GPIOs

The following commands require root privileges. Use sudo su to switch to the root user.

Identify GPIO Subsystem Numbers

Identify the base GPIO number by running the following command and looking for platform/f000000.pinctrl (gpiochip4).

mount -t debugfs none /sys/kernel/debug/
cat /sys/kernel/debug/gpio

LS1 Connector GPIO
GPIO	Odd	Even	GPIO
GND	1	2	GND
52	3	4	CAN_H
54	5	6	CAN_L
55	7	8	32
53	9	10	33
44	11	12	34
45	13	14	35
96	15	16	107
95	17	18	106
100	19	20	109
99	21	22	108
40	23	24	105
41	25	26	43
42	27	28	SAIL59
PME 11	29	30	SAIL42
140	31	32	SAIL46
IO EXP3 7	33	34	SAIL50
3.3V	35	36	SYS PWR
5V	37	38	SYS PWR
GND	39	40	GND

Configure GPIOs from User Space

Use the libgpiod library from user space to control the GPIOs for better performance.

Install the Arm64 toolchain

sudo apt install gcc-aarch64-linux-gnu
sudo apt install binutils-aarch64-linux-gnu

Download and extract libgpiod

wget https://www.kernel.org/pub/software/libs/libgpiod/libgpiod-1.6.4.tar.xz
tar xvf libgpiod-1.6.4.tar.xz
cd libgpiod-1.6.4

Configure the sources for static linking

./configure --enable-tools=yes --build x86_64-pc-linux-gnu --host aarch64-linux-gnu CFLAGS="-static -static-libgcc -Wl,-static,--start-group,/usr/lib/gcc-cross/aarch64-linux-gnu/7.5.0/libgcc.a,/usr/lib/gcc-cross/aarch64-linux-gnu/7.5.0/libgcc_eh.a,/usr/aarch64-linux-gnu/lib/libc.a,--end-group"

Compile the library

make

Compiling creates linked binaries.

Build the statically linked binaries

aarch64-linux-gnu-gcc -static -o tools/gpiodetect tools/gpiodetect.o tools/tools-common.o -Wl,-L&lt;ABSOLUTE_PATH_TO_LIBGPIOD&gt;/libgpiod-1.6.4/lib/.libs,-lgpiod,-lpthread,-static
aarch64-linux-gnu-gcc -static -o tools/gpioget tools/gpioget.o tools/tools-common.o -Wl,-L&lt;ABSOLUTE_PATH_TO_LIBGPIOD&gt;/libgpiod-1.6.4/lib/.libs,-lgpiod,-lpthread,-static
aarch64-linux-gnu-gcc -static -o tools/gpioset tools/gpioset.o tools/tools-common.o -Wl,-L&lt;ABSOLUTE_PATH_TO_LIBGPIOD&gt;/libgpiod-1.6.4/lib/.libs,-lgpiod,-lpthread,-static
aarch64-linux-gnu-gcc -static -o tools/gpiofind tools/gpiofind.o tools/tools-common.o -Wl,-L&lt;ABSOLUTE_PATH_TO_LIBGPIOD&gt;/libgpiod-1.6.4/lib/.libs,-lgpiod,-lpthread,-static
aarch64-linux-gnu-gcc -static -o tools/gpioinfo tools/gpioinfo.o tools/tools-common.o -Wl,-L&lt;ABSOLUTE_PATH_TO_LIBGPIOD&gt;/libgpiod-1.6.4/lib/.libs,-lgpiod,-lpthread,-static
aarch64-linux-gnu-gcc -static -o tools/gpiomon tools/gpiomon.o tools/tools-common.o -Wl,-L&lt;ABSOLUTE_PATH_TO_LIBGPIOD&gt;/libgpiod-1.6.4/lib/.libs,-lgpiod,-lpthread,-static

Push the binaries to the device

scp gpiodetect gpioget gpioset gpiofind gpioinfo root@<IP_address>:/path/to/directory/on/device

List GPIO chips on the device

Run gpiodetect to list the GPIO chips.

./gpiodetect

Example output:

gpiochip0 [c440000.spmi:pmic@8:pinctrl@c00] (12 lines)
gpiochip1 [c440000.spmi:pmic@1:gpio@8800] (10 lines)
gpiochip2 [c440000.spmi:pmic@2:gpio@8800] (9 lines)
gpiochip3 [c440000.spmi:pmic@0:gpio@b000] (4 lines)
gpiochip4 [f100000.pinctrl] (176 lines)
gpiochip5 [33c0000.pinctrl] (15 lines)

Display GPIO line information

Run gpioinfo to view the lines for a specific chip.

./gpioinfo gpiochip4

Example output:

gpiochip4 - 151 lines:
    line   0:      unnamed          "?"   input  active-high [used]
    line   1:      unnamed       unused   input  active-high
    line   2:      unnamed      "perst"  output   active-low [used]
    line   3:      unnamed       unused   input  active-high
    line   4:      unnamed      "perst"  output   active-low [used]
    line   5:      unnamed          "?"   input  active-high [used]
    line   6:      unnamed       unused   input  active-high
    line   7:      unnamed       unused   input  active-high
    line   8:      unnamed       unused   input  active-high
    line   9:      unnamed       unused   input  active-high
    line  10:      unnamed       unused   input  active-high
    line  11:      unnamed       unused   input  active-high
    line  12:      unnamed       unused   input  active-high
    line  13:      unnamed       unused   input  active-high
    line  14:      unnamed       unused   input  active-high
    line  15:      unnamed       unused   input  active-high
......
.....

Set a GPIO value

To set GPIO line 54 on gpiochip4, run:

./gpioset gpiochip4 54=1
./gpioinfo gpiochip4 | grep 54

Example output:

gpiochip4 - 176 lines:
   line    54:      unnamed       unused   output  active-high

Read a GPIO value

To read GPIO line 0 on gpiochip4, run:

./gpioget gpiochip4 0

Example output:

After reading the value, gpioinfo shows the line returned to input mode.

./gpioinfo gpiochip4

Example output:

gpiochip4 - 176 lines:
         line    0:      unnamed       unused   input   active-high
         line    1:      unnamed       unused   input   active-high

UART

Pins 5 and 7 are configured for UART by default (GPIO lines 54 and 55, mapping to uart12 = qup1_se5 (0xa98000)). Follow the Modify serial engine node procedure to enable the UART interface. After enabling, the device node appears at /dev/ttyHS3.

Shell

Connect pins

Short pin 5 and pin 7 with a Dupont wire.

Do not short power and ground pins.

Configure UART

stty -F /dev/ttyHS3 ispeed 115200 ospeed 115200
stty -F /dev/ttyHS3 115200 -echo -icanon -isig -iexten -icrnl -ixon -opost

Open two SSH terminals

Terminal 1 (RX): cat /dev/ttyHS3Terminal 2 (TX): echo "hello world!" > /dev/ttyHS3

I2C

Pins 8 and 10 are configured for I2C by default (GPIO lines 32 and 33, mapping to i2c4 = qup0_se4 (0x990000)). Follow the Modify serial engine node procedure to enable the I2C interface.

ls /dev/i2c*
scp i2cdetect root@<IP address>:/usr
i2cdetect -l
i2cdetect -a -y -r 20

SPI

Pins 11 and 13 are configured for SPI by default (GPIO lines 44 and 45, mapping to spi10 = qup1_se3 (0xa8c000)). Follow the Modify serial engine node procedure to enable the SPI interface.

​Pinout

​GPIOs

​Identify GPIO Subsystem Numbers

​Configure GPIOs from User Space

​UART

​I2C

​SPI

Pinout

GPIOs

Identify GPIO Subsystem Numbers

Configure GPIOs from User Space

UART

I2C

SPI