Sunday, September 19, 2010

68HC11 Bootstrap mode

In 1999, I received a Super T-Comp; a 68HC11 based microcontroller board that is similar to the Handyboard.
While working with it I released the sacred smoke. I blew out 3 chips.
I repaired the damage, but I couldn't get it to work right again. So it sat in my toybox waiting for me to try again.

In 2010, I am taking a class in embedded systems; so it is time to try again.

Inspecting the board again, I found a bad chip that I missed; a NAND gate driving the external RAM. I will fix that this week.

Regardless I should be able to talk to T-Comp in Bootstrap mode. PCBug11 is the original tool for talking to 68HC11. It doesn't run on modern (fast) computers.

So I tried TeraTerm terminal software. Finally did established communication this morning.

68HC11 has 4 modes:
Single Chip: no external RAM
Expanded: external RAM
Bootstrap: single chip, using bootstrap loader in ROM
Test: Uh? don't know

Bootstrap Mode
Hold ModA and ModB low
Toggle Reset
Release ModA and ModB
within a second
send a byte over SCI (serial port) at 1200 Baud, No parity, 8 bits, 1 stop bit.

It is now ready to accept a 256 byte program. 68HC11 will echo bytes. Once it recieves 256 bytes, the program counter resets to $0000 and starts to run the loaded program. In theory.

Saturday, September 18, 2010

Hacking the PSP

Everyone has hacked the PSP to put non-Sony firmware on.
You can still run your games, AND install homebrew stuff.

This was the original goal when I bought my PSP. I got distracted by actually playing games.
I finally got around to doing it.

I have the GOW edition PSP slim, it had Sony firmware V3.94 installed.

I sort of followed the instructions that I found here

Things you need:
Pandora Battery - modified battery to allow access to the PSP bootstrap mode,
I borrowed one
Sony memory stick - 1Gb stick works fine
PSP Grader v0.008 - installs firmware, I got it here
modified PSP firmware - overwrites the Sony firmware, I got it here

Connect the PSP to your PC; start USB mode.
Copy the Sony memory stick to PC
Format the Sony memory stick

Start PSP Grader
Locate the eboot.pbp in the
Download file to stick

Disconnect and power off the PSP
Remove battery
Insert memory stick (if you haven't)
Hold down the L button
Insert the Pandora Battery (often PSP auto-starts) and start PSP
Back up NAND
Restart PSP
Install 5.00 M33 (or similar)

I have spent all my time playing a Magic the Gathering Homebrew (Wagic) in stead of programming anything.