The HP 34E Ir with PANAMATIK ACT

[PANAMATIK]

(09-23-2015 05:44 PM)Harald Wrote:  The cable is my WP34s flash cable prototype which I hacked from an old USB to RS485 adapter. But any USB to UART cable should do.

The USB needs to be plugged in first, the Calculator after starting Bernhards flash tool. This is necessary because of the way he gets into the bootloader.
You have to take care that Vcc is the last connection to be made on the jack. If this isn't the case you can (and will, as I found out the hard way) damage Bernhards ACT.

The ACT Flash Update tool pulls the TX line to low level. When the ACT is powered up it reads the TX line and if low enters the boot loader waiting for data. Therefore GND and TX must be connected before VCC is applied, otherwise the boot loader reads high level at startup and immediately starts the calculator. When I designed the boot loader I thought about waiting TX going low for some 100 ms at each power up, but I decided that the 0.00 must appear immediately after moving the On/Off switch to behave exactly like the original calculator.

If contacting VCC first, the ACT will not be damaged, but appears to be damaged, because it never enters the boot loader.

Bernhard