SDCard speedup : don't re-calculate CRC table, allow faster SPI data rate #23
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i wonder if we'd be able to play audio off sd card, something that did not work before :) |
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For audio playback, it’s something I’m going to try in the next days, as it would help me in my project. But I fear that reading samples in the background won’t work : auto-refreshing the display always lock the board up. I had to use manual refresh to make it work. I fear that we can’t call python code in sdcard.py in the background while running python code in the main loop. That’s why a C version of sdcard.py would be usefull, more than speed improvements. |
tannewt
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Oct 17, 2019
…faster SPI data rate
tannewt
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Oct 18, 2019
adafruit-adabot
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Nov 18, 2019
Updating https://github.com/adafruit/Adafruit_CircuitPython_SD to 3.2.5 from 3.2.4: > Merge pull request adafruit/Adafruit_CircuitPython_SD#29 from dhalbert/avoid-longint > Merge pull request adafruit/Adafruit_CircuitPython_SD#26 from Anton-2/master > Merge pull request adafruit/Adafruit_CircuitPython_SD#24 from adafruit/dherrada-patch-1 > Merge pull request adafruit/Adafruit_CircuitPython_SD#23 from Anton-2/master
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Tested on a pyportal, with CircuitPython 5.0.0 alpha 4.
My ad-hoc benchmark is 20 refresh of the screen, with a 64x64 OnDiskBitmap on the SDCard.
Original adafruit_sdcard.py takes 19 s.
By removing the CRC table re-calculation, we are down to 1s.
Maxing the data rate at 24Mhz makes it 0.7s.
Other changes involve reading status bytes first before testing them. It's marginally faster, and more correct on line 257 where it was not initialized.