SPI like protocol DEMO interfacing via6522 (Oric Atmos) with teensy 3.2 using no breadboard, and no soldering, but only 11 dupont cables
Project state : alpha release (no license)
Connections: (5 cables) (6 cables) Oric Atmos VIA 6522 <---> teensy 3.2 <---> SD catalex SPI module D1 2 SCK(13) SCK D2 3 DOUT(12) MOSI D0 4 DIN(11) MISO D3 5 CS(10) CS VIN(+5V) VIN GND GND GND GND
-project on Teensy3.2: "porta_spi3.2.ino" warning i have to modify a library for correct SPI speed between teensy and catalex ... test with standard sketch before !
warning don't mess with the analog and digital pins on teensy, only digital pins are 5v tolerant. if you send more than 3.3v in analog inputs , you are sure to burn the Teensy.
-project on Oric Atmos: "SPI_LOAD.TAP" : the main boot loader application (about 840 bytes loader routines, tape duration is about 6 sec)
-> send "BOOT" command to Teensy sources: spi_load.s /osdk_config.bat
"ORIC_SPI.TAP" : the Oric Atmos SPI link to Teensy demo ( tape duration about 45 sec, loaded in a couple of seconds with spi boot loader) sends commands to teensy3.2 via spi link "DIR" shows directory of sd card "TAPE" loads a tape in oric memory from sd card - supported tapes are hires images or binary executables only (full tape support in todolist) "SAVE" loads a saved image in PROGMEM in oric memory "LOAD" loads a saved image on SD card in oric memory "TEXT" loads a text file on SD card in oric display sources: main_oric_spi.c / oric_spi.s / osdk_config.bat
History:
As I wanted to make speaking my oric atmos with external world via serial at first, I went to interface it with a microcontroller,
trying with a teensy++2.0, it worked but was a bit slow in bauds as on oric side , I have to wait for the data to be read on
microcontroller side... So I've changed for a more powerful teensy running at 96Mhz (it works at 72Mhz), enable to catch at
microsecond scale the changes on digital pins, no more delay on Oric side, best speed achieved !
-Raw transfert (no checksum) from teensy progmem to oric ram done at 65K bauds
-Transfert from sd to oric with checksum calculation/check done at 52K bauds
Credits & Special thanks to: OSDK, ALL oric user forums ! (forum-defence.force.org, retrowiki.es, ceo ...), SPI protocol on wikipedia, implementations in 6502, VIA documentation (and pages talking about !), Ana de Armas (for my repeating slide show pictures) ...