HP30b flashed with WP31 no longer responding

[matthiaspaul]

(01-20-2016 03:55 PM)mfleming Wrote:  

Quote:Maybe I should emphasize the importance of good connections a bit more in the Troubleshooting Guide.

And this confirms the observation in the manual that no one has ever damaged a calculator by flashing it. There are however, ways to make it seem so!

From the electrical point of view it is quite easily possible to permanently damage the calculator during flashing in two possible scenarios:

- ESD (as an internal port, the flash port does not have any dedicated ESD protection as it would be a design requirement for any user-accessible ports, so touching one of the wires while being charged can be sufficient to kill the I/O port already)

- leaving (almost) exhausted batteries in the calculator while flashing the calculator through one of the cheaper flashers not adjusting the logic levels to the device's VCC (that is, virtually all flashers except for "high-end" ones). (The typical scenario would be a flasher operating at 3.3V and batteries with less than 3.0V). This will easily overload the clamping diodes in the processor's I/O port. This problem can be avoided either by removing the batteries while flashing (requires the calculator to be powered externally through the flash port), by inserting fresh batteries before flashing, or by adding large enough series resistors into the data lines (which may have other downsides).

Obviously, none of this was the reason for your original flashing problems. I guess, in most cases, problems are caused by corrupted flash images, bad cable connections or an otherwise interrupted flash process all causing the calculator's firmware to "hang" after flashing. These problems should be fixable through JTAG programming. Still, it would be misleading to state that it is impossible to permanently damage the calculator during flashing.

Greetings,

Matthias