20mhz / wavehc Goto Github PK

What steps will reproduce the problem?
1. Running the example daphc on the programming port for Due

What is the expected output? What do you see instead?
daphc.pde: In function 'void play(FatReader&)':
daphc.pde:105:62: error: 'strncmp_P' was not declared in this scope

What version of the product are you using? On what operating system?
wavehc20110919.zip

Please provide any additional information below.

What steps will reproduce the problem?
1. Plug in Arduino, upload sketch - works
2. Press reset on shield - playback very choppy/distorted
3. Press reset on shield again - serial output shows ""No valid FAT partition!"
4. Press reset on shield 3rd time - serial output shows SD I/O error: 6
5. Powering off Arduino or reseating the SD card resets behavior to step 1

What version of the product are you using? On what operating system?
WaveShield 1.1, wavehc20101009, Arduino Uno, OS X. Included SD card, Transcend 
MicroSD (w/adapter) 2GB.

Please provide any additional information below.
I searched for issues related to the ACMD41 stage of SD card init, lots of hits 
but what set this apart was that it worked at first, then degraded.

I noticed that people described the spec requiring <400kHz SPI clock during the 
card init phase.  The current wavehc library sets the clock to 125kHz 
(f_osc/128), which is just under 1/3rd the max recommended init clock rate.  I 
tried the highest available option below 400kHz, 250kHz (f_osc/64), and 
success! I can now reset as many times as I want and no issues.

I changed the following lines in SdReader.cpp SdReader::init
  // Enable SPI, Master, clock rate f_osc/128
  SPCR = (1 << SPE) | (1 << MSTR) | (1 << SPR1) | (1 << SPR0);
To:
  // Enable SPI, Master, clock rate f_osc/64
  SPCR = (1 << SPE) | (1 << MSTR) | (1 << SPR1);

So, for at least this model MicroSD card, it appears 125kHz is too low a clock 
for the card's liking during init.