FOX Board G20 V2 BETA tips

The following information is valid for the FOX Board G20 V2 BETA

 Note:   The FOX Board V2 was an experiment and will not be available as standard product.

Kernel and rootfs differences

One of the most important differences in the compiled kernel is that the 1-wire bus should be placed on PA29 instead of PB16

A 1-wire driver for the DS28EA00 was written to manage this chip and is available inside the /root directory.

The /etc/rc.local was added to the following snip of code:

insmod /root/w1_ds28ea00.ko
sleep 5
dir=`ls /sys/bus/w1/devices/ -1 | grep 42`
echo 1 > /sys/bus/w1/devices/$dir/pio_value

This will ensure that the kernel driver is loaded then the pio1 of the w1 chip is placed HIGH, according to FOXG20v2 schematics this means that the USB's are powered. To disable the usb simply write "0" in the same file.

Tips and variant

Shut-down the netus

According to the schematics the 1-wire is also present on J6, this allows you to shut-down the netus and the USBs by using an external MCU placed on the same 1-wire bus.

The dangerous side-effect is that you can you can also issue a command through the kernel driver that shuts down the netus in hardware.

#don't do this!
dir=`ls /sys/bus/w1/devices/ -1 | grep 42`
echo 3 > /sys/bus/w1/devices/$dir/pio_value 

Override the 1-wire USB power capability

Placing a short circuit in place of L3 you can override the power capability offered by the 1-wire chip.

Using the second sdcard

To use the second sdcard you should recompile the kernel and enable it inside arch/arm/mach-at91/board-foxg20.c and rewrite the mmc_data as follows:

static struct at91_mmc_data __initdata foxg20_mmc_data = {
       .slot_b         = 0,
       .wire4          = 1,
};

Then you can enable the second sd card slot in SPI mode adding it to kernel structure as appear in: https://github.com/AcmeSystems/linux/commit/70e87c71a0b3e51d5b762c13888534b9ce90e342

You can also refer to the branch https://github.com/AcmeSystems/linux/commits/acme-3.2 for some related improvements.

You should also place a short circuit in R73 and remove R72.

Bottom placement of the component