JTAG on HP-12C and HP-15C LE

[Ingo]

I'm wondering if anyone tried to read out the mem of the HP-12C or HP-15C LE via the 6pin JTAG (I assume) adapter that is located beten the two battery cells.? This could be a semi-convenient way to load and store programs.

[Marcus von Cube, Germany]

You can't!

The connector is a custom serial interface. In order to read out the flash memory you'll need to put the chip in a special SAM-BA boot mode. This can only be done by clearing flash memory which means you are loosing the firmware. Even with the boot bit set correctly, RAM cannot be easily accessed because it's being overwritten by the download software and/or lost by resetting the device.

[Ingo]

What a pity! Thanks for enlightening me :)

I was just curiouos, as the Atmel Datasheet says that the JTAG Interface supports Flash read via JTAG, and the 6pin header looked to me like exactly that.

Edited: 1 July 2013, 5:24 p.m.

[Harald]

I haven't opened up the 15C LE, but maybe it has the same option to be fitted with a JTAG as the 30B has. But even then you would probably need the software in order to create a memory map.

[Katie Wasserman]

There's no JTAG interface in the 15LE (and 12C+) Even if there were it would have the same issue as Marcus described.

[Paul Dale]

More interesting would be to port Eric's nonpareil to the hardware so that the bugs can be fixed.

- Pauli