Wreck it Ralph Raspberry Pi project.

Here is a video of the Pac-Man game in action. Still needs some more work done.

Testing how the PacMan program behaves without PacMan around.

Making use of the memory mapping was a fairly simple way of moving around machine code without complications.

CHAR0-CHAR3 is where I put the moveable characters.

MEMORY {
    CPU_0C    : ORIGIN = 0x08000, LENGTH = 0x008000
    CPU_0D    : ORIGIN = 0x10000, LENGTH = 0x008000
    
    DATA    : ORIGIN = 0x18000, LENGTH = 0x800000
    
    CHAR0    : ORIGIN = 0x880000, LENGTH = 0x010000
    CHAR1    : ORIGIN = 0x890000, LENGTH = 0x010000
    CHAR2    : ORIGIN = 0x8A0000, LENGTH = 0x010000
    CHAR3    : ORIGIN = 0x8B0000, LENGTH = 0x010000
}


SECTIONS {
    .CPU0_C : {
        *(.init)
        *(.CPU0_ASM_)
        *(.CPU0_C_)
    } > CPU_0C
...

Testing dynamically relocatable assembly subroutines for characters, works on local machine, remote machines are next to test.

Recently obtained a RPI 3, testing to see if it can be a suitable central hub, Aarch32 mode may differ enough to cause compatibility issues.

The Raspberry Pi has a independent Master I2C device, and a independent Slave I2C device. It is interesting that a Raspberry Pi can talk with itself, due to the fact that both units are separate from each other.

Data transmissions are limited to 400,000Hz, which is very slow for multi megabyte entities to be transferred quickly. I'm trying to keep the transfer times below 5 seconds, that limits the data to about 128Kb per entity/character. Now I need to test with live subroutines.

I might end up using a 10 pin(8 Bit) parallel bus to speed up the transfers.

Poling the NES/SNES controllers takes up way to many CPU cycles, so I've decided to use interrupts for them, the ARM timer works pretty well for this, the BSC~I2C Master/Slave units both generate their own interrupts. This is really only an issue with the 2835 chip, the 2836 is a quad core, so one core can poll everything over and over again, without much of an issue of waisted CPU cycles.

Got the frame buffers up and running on all systems. Programmed a simple title screen for Fix It Felix Jr. and Pac-Man.