A Mutable Log

A blog by Devendra Tewari

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SparkFun FTDI Basic with Raspberry Pi

The following diagram shows how you can connect an FTDI Basic (USB to serial) breakout board to Raspberry Pi’s GPIO connector. If you’ve configured VCC to output 5 Volts, you can also power the Raspberry Pi by connecting its 5V header pin to VCC.

pi-ftdi-basic

If you’ve got Adafruit’s USB to Serial TTL cable, you can follow their lesson on using it.

Output kernel log to console

For the kernel log to appear on the serial port, console should be set to ttyAMA0.

Here’s how cmdline.txt in the boot partition of my Raspberry Pi looks like

dwc_otg.fiq_fix_enable=1 sdhci-bcm2708.sync_after_dma=0 dwc_otg.lpm_enable=0 console=ttyAMA0,115200 root=/dev/mmcblk0p2 rootwait

To get a login prompt /etc/inittab should contain a line such as

ttyAMA0::respawn:/sbin/getty -L ttyAMA0 115200 vt100 # GENERIC_SERIAL

If you’re compiling your own kernel using Buildroot, set the TTY port to ttyAMA0 under System configuration, getty options

ttyAMA0