UART0
From t-hack.com - Hack X300T / X301T
General information on the Serial Ports
There are two serial ports on the SMP8634: UART0 and UART1.
UART1 pins are shared with the JTAG pins, so it is either JTAG or UART1.
On the X300T the JP1 switches between JTAG and UART1.
UART0 is used to output some debug information during startup, unfortunately most of the debug output in the Bootloader was disabled, so there is not much to see during startup.
the serial port settings are 115000 baud and 8N1
xosPc8 serial#e3eec781720b9f8258d2b8d9xxxxxxxx subid 0xc4 xenv cs2 ok power supply: ok dram0 ok (7) dram1 ok (7) zboot ok SIGNED BL Microsoft IPTV Bootloader, Build (1039) Built by BM-DELL-167, Jul 13 2006 20:19:03
the first lines up to "zboot ok" are printed by the XOS. The first output of the IPTV Bootloader is "SIGNED BL".
The only interesting information on this output is the bootloader version ... 1039 in this case.
How to built a debug interface
The needed pins are show in the image on the right (NOTE: vcc-pin (5V) is on the left hand side next to the ground pin) Please note that the voltage level of the I/O pins is 3.3V so you will need a voltage level convertor to interface with a standard PC serial port.
This can be done with a Max3232 chip, but I would advise to use a "3.3Vserial port -> USB connector".
You can find cheap mobile interface cables that perfectly fit:
- original Siemens data cable DCA-510 (USB)
- original Siemens data cable DCA-500 (serial)
- NOTE: since the 3,3v level-converter is not powered from pc, one need to connect the vcc pin in order to power the max3232. however, this is only needed for the original cables, no-name cables are usually powered from pc
Both can be grabbed from ebay for some euros.
The below picture shows the connector pinout for the Siemens S55 (and others):
- Vin
- Gnd
- Tx
- Rx
- CTS
- RTS
- DCD
- Audio P
- -
- Audio N
- GND
- EPP
