There are 4 major differences against Rev 0.2.
1. Micro-USB port can work in USB host mode too.
2. USB host power protector IC was changed to NCP380 from AP2411.
3. HDMI reverse-current blocking IC AP2331 was placed on the correct place.
4. HW SPI port
You can see the schematics of Rev 0.5 in this link.
http://www.hardkernel.com/main/products ... &tab_idx=2
U3 IO Shield board was also updated to Rev 0.3 from Rev 0.2 by adding a SPI Flash memory.
http://www.hardkernel.com/main/products ... &tab_idx=2
HW SPI port
The Serial Peripheral Interface or SPI bus is a synchronous serial data link that operates in full duplex mode.
- spi.png (5.55 KiB) Viewed 6903 times
To access the SPI/GPIO on new J5 connector, you must update kernel first.
The SPI modules were enabled at July 17, 2014.
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wget http://builder.mdrjr.net/tools/kernel-update.sh
chmod +x kernel-update.sh
sudo ./kernel-update.sh
The SPI bus is added on new J5 (IO Port#2) 4-pin connector on PCB.
Note that SPI port supports only master mode and 1.8 Volt interface like other IO ports on Exynos processor.
- board.png (665.2 KiB) Viewed 6903 times
Pin Descrption
- pinmap.png (15.47 KiB) Viewed 6903 times
You can use 4 pins as GPIO mode or SPI mode. After booting, the pins are in GPIO mode by default.
This example script sets all pins to output and toggle 5 times at 1Hz frequency.
At the beginning, it unloads the SPI driver modules to make sure the GPIO mode.
At the finishing, it releases the GPIOs for the next usage.
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modprobe spi-s3c64xx
modprobe odroid-ioboard
dmesg | grep ioboard
modprobe -r odroid-ioboard
modprobe -r spi-s3c64xx
count=0
stop=5
echo 20 > /sys/class/gpio/export
echo 21 > /sys/class/gpio/export
echo 22 > /sys/class/gpio/export
echo 23 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio20/direction
echo out > /sys/class/gpio/gpio21/direction
echo out > /sys/class/gpio/gpio22/direction
echo out > /sys/class/gpio/gpio23/direction
while :
do
count=$(($count+1))
echo 1 > /sys/class/gpio/gpio20/value;
echo 1 > /sys/class/gpio/gpio21/value;
echo 1 > /sys/class/gpio/gpio22/value;
echo 1 > /sys/class/gpio/gpio23/value;
echo "GPB[4],GPB[5],GPB[6],GPB[7] set output HIGH"
sleep 1;
echo 0 > /sys/class/gpio/gpio20/value;
echo 0 > /sys/class/gpio/gpio21/value;
echo 0 > /sys/class/gpio/gpio22/value;
echo 0 > /sys/class/gpio/gpio23/value;
echo "GPB[4],GPB[5],GPB[6],GPB[7] set output LOW"
sleep 1;
if [ $count -eq $stop ]; then
echo "GPIO TEST STOP"
echo 20 > /sys/class/gpio/unexport
echo 21 > /sys/class/gpio/unexport
echo 22 > /sys/class/gpio/unexport
echo 23 > /sys/class/gpio/unexport
exit 0
fi
done
Let’s try the SPI mode.
How to load the SPI driver module for generic SPI usage!
Load the module to activate the SPI host.
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$ sudo modprobe spi-s3c64xx
Load the module to activate the generic SPI.
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$ sudo modprobe spidev
And you will have a standard SPI node.
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$ /dev/spidev1.0
How to load the SPI driver module for serial Flash!
Load the module to activate the SPI host.
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$ sudo modprobe spi-s3c64xx
Load the serial flash (misc) driver
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$ sudo modprobe odroid-ioboard
And you will have a Serial Flash node
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$ /dev/ioboard-spi-misc
Where are the SPI device drivers in Kernel 3.8.y?
- SPI host interface driver:
https://github.com/hardkernel/linux/blob/odroid-3.8.y/drivers/spi/spi-s3c64xx.c
- SPI generic driver
https://github.com/hardkernel/linux/blob/odroid-3.8.y/drivers/spi/spidev.c
- Serial SPI Flash add-on driver example
https://github.com/hardkernel/linux/blob/odroid-3.8.y/drivers/hardkernel/ioboard-spi-misc.c
Note that spidev.ko and odroid-ioboard.ko can’t be loaded at the same time.
We’ve tested the ioboard-spi-misc.ko with a Serial SPI Flash memory SST25WF020A on the new IO Shield and the maximum speed was 40Mhz of SPI clock.
Refer this link to know the generic SPIDEV driver usage in detail.
https://www.kernel.org/doc/Documentation/spi/spidev
