Fintec 904 - Poke & Peek

Just a curiosity.

Serial EEPROM

There is a bug in some MT1379 firmwares that inhibits changing the players region with remote control. You can enter to the secret region menu, but the player does not respond to any remote button. Only option is reprogramming the serial EEPROM. My player does not suffer from the bug. But however, I wanted to see what lay beneath the surface.

	The Chip Atmel 24C16N hardwired.
	The Easy Rider Easy I2C Bus Adapter. These 2 transistors and 4 resistors fits easily inside DB25 case, but I prefer vero-board for my gadgets.
	The Dump I red the contents of the eeprom with Lanconelli's PonyProg. That site has also schematics for the Easy I2C adapter. I changed my player to regions 0, 1 and 2, and then made a binary dump from the eeprom in each region. It seems that data has some sort of encryption/compression. Instead of one byte change everything changed (excluding MT34 header).

Serial Port

The mainboard has a 4-pin header with markings DV33, RXD, TXD and GND, which gave me hope that Fintec may have a serial console port. A quick check with voltage meter confirmed that port has 3.3V CMOS level signals and it needs RS-232 converter.

	The Converter MAX3232 compatible 3.0 - 5V transceiver.
	The Adaptor This is the schematic of the board I used. It is found from MicroChip's PICMicro manuals (IIRC). Capasitors are either 1uF or 100nF depending on the MAX chip. Resistor should be atleast 1/4 W. Adding pull-down resistors to unused inputs may be an excellent idea. They reduce interference and power consumption caused by undetermined state of the inputs. Information is provided AS IS. ...< Insert standard disclaimer here >... Viewers discretion advised.
	The Response After trying various serial port settings I got a trashed response proofing that something was really happening. This gave me a hint about possible bit rate. 100us/div.
	The Pulses lows are 80us and highs are 60us. 20us/div.
	The Double U 'U' @14400,8,n,1. Rumours whisper that there is a mysterious MTKTOOL which makes possible firmware upgrades via serial port. Bit rate is supposed to be 115200 bps
	The Tool Yes, indeed. The rumours are true. I was fortunate that I did not break anything when trying. There is such command as 26h (erase flash). Type fintec904_serial.zip to the URL to get the original serial firmware.

Continue to
Part 1: Overview
Part 2: Hardware Tuning (power switch, mic)