search

dhansel / ArduinoFDC

Library for using an Arduino as a floppy disk controller
GNU General Public License v3.0
272 stars 41 forks source link

Migrate to stm32 #15

Open TEN1HC opened 1 week ago

TEN1HC commented 1 week ago

FDD_Stm32_v03.zip Im trying to migrate this lib to Stm32f103c8t6. Using timer1 for input capture Using timer3 for some index/pusle ..,check Using timer2 for pwm out write data (not implemented yet)

Failure detected as f_open method => DISK_ERROR

So many thing to do and it still not work. Could you help to check?

Thank you so much for this project, it is working perfectly on arduino

dhansel commented 1 week ago

I had a look at your low-level reading code (function read_data in FDD.cpp), and it looks you don't quite have a good grasp yet of how the MFM encoding on floppy disks works. It's not as simple as "short time between pulses=0" and "long time=1". The read_data() function in my code does quite a bit more than that (but of course it's very specific to the Atmega328p and therefore can't be used for STM32). I recommend reading up on the basics of MFM encoding and how to read floppy disks. There's some good information here: https://www.5volts.ch/posts/mfmreader https://www.hermannseib.com/documents/floppy.pdf

Apart from that you have to be sure to get your timing right. There may only be 2us of time between two pulses received from the drive. I don't know anything about STM32 but you may want to double-check the interrupt latency since your CaptureCallback function relies on interrupts. If the latency is too high you may miss some pulses. Also make sure that other interrupts don't get in the way,

This is definitely not an easy project to port to a different platform. It took me months of working with an Oscilloscope and Logic Analyzer to get the timings right on the Atmega328p. I would suggest testing at a lower level than the f_open() call. When I developed ArduinoFDC I started with the low-level disk monitor that allowed me to just read (and write) data to one sector. I started with a known-good formatted disk and used a program such as OmniFlop on a PC to get the expected content of a sector. Then on ArduinoFDC read that same sector to see what I got. Use an Oscilloscope to really look at the timing, the points when you read the data bits etc. Debug, rinse and repeat. It's a long process but very rewarding once you finally get it right (and you'll learn a lot about debugging tools and techniques along the way).

Good luck!

TEN1HC commented 1 week ago

Great to receive reply from you. I realize that Im so naive when just give a simple pulse read method like that. Thank you very much for the reference documentation.