need help with w34s cable

[Marcus von Cube]

Why are you building a RS232 cable? This makes most sense if you have an older PC which offers a standard serial port. For all other cases, a direct connection to a FTDI USB-to-3V-TTL-serial converter (see http://www.ftdichip.com/Products/Cables/...Serial.htm) is the better solution. The newer cables even deliver 3.3V power and can be directly connected to VBat (remove the batteries first!).

The pinout of the programming connector can be found in the HP20b schematics delivered with the SDK (Ask TW for the URL). Here is a picture of the connector:     .

The pins are as follows: 1=VBat, 2=Reset, 3=Tx, 4=Gnd, 5=Rx, 6=Erase.

Erase must be connected to VBat while the processor is running to erase the firmware and enable the boot loader. Press ON while shorting pins 1&6. Then power off the calculator (reset or battery pull) and turn it on again with ON. Now it is ready to receive commands from MySamba or other programming software.