Firmware Debugging
From ThinCan
Contents |
VGA/DDC muxed serial port
The ThinCan Geode LX models DBE61, DBE62 and DBE63 offer a serial console, for firmware debugging purposes, on the DDC pins of the VGA connector. Enabling it requires configuring GPIO3 (UART2-RX / DDC-SCL) and GPIO4 (UART2-TX / DDC-SDA) to send the console output to VGA connector VESA DDC2 pins, instead of reading EDID info as in production hardware.
Artec Group has developed a breakout board with RS232 to TTL converter to be used with ThinCan. The board has DB15 connectors for VGA pass-through and DB9 connector for serial connection.
VGA DB-15 connector pins for serial console (3.3V TTL signal levels):
12: TX - data from DBE61
15: RX - data to DBE61
5: GND - common ground
9: VCC5V - converter power
NB! PIN9 is missing or not connected on many VGA cables. When using a VGA cable to create your converter, check that it has all pins connected!
Second serial port
DBE62 and DBE63 models have a header on the board for second serial port. The port has 3.3V TTL signal levels; a TTL-RS232 converter is needed. Artec has designed extension board for DBE62 second serial port.
Serial TTL-RS232 converters
Artec has developed special converter for ThinCan VGA DDC serial port.
If you prefer to build your own, the easiest way to build own serial cable for Thincan is obtain cell phone data cable, preferably for older models, where usual TX/RX serial protocol used (newer cell phones tends to talk with USB directly). Siemens data cables known to work, both RS-232 and USB variants.
You can also build your own cable, for example using MAX232 (RS232) [1] or FT232 (USB) [2].
Another option is to break apart an existing USB-serial converter. USB-serial converters consist of 2 parts: USB-"TTL serial"(usually FT232 or PL2303) and "TTL serial"-"RS232 serial"(usually MAX232 or similar) converters. It is possible to remove the second chip and use just the USB-TTL converter to debug ThinCan using USB-serial port.
As the flow control lines are not connected on ThinCan, the user should connect RTS with CTS on the converter to avoid problems. As the flow control is not used, it should be disabled in terminal application.
Reset
Board can be reset with shorting reset pin to ground. On DBE61 and DBE62, reset and ground pins can be found on internal JTAG connector J2 as follows (pin 1 marked with square pad):
10 -o o- 9
8 -o o- 7
6 -o o- 5
4 -o o- 3
GND 2 -o o- 1 RESET
On DBE63, the reset pins are in a separate header marked as "RESET".
![[1]](http://pinouts.ru/images/cable_cell.gif){kind=link}