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December 29, 2010
about 8 months ago
For those connecting a USB-to-Serial cable like CAB-12977 to the Raspberry Pi B+ (or any Pi) console, avoid the newbie mistake of misconnecting transmit and receive: the connections should be:
GPIO connector pin 6 to cable pin labeled GND;
pin 8 (TXD0) to cable pin labeled RXD;
pin 10 (RXD0) to cable pin labeled TXD.
That is, connect transmit to receive and receive to transmit (duh); not transmit to transmit and receive to receive..
Luckily, connecting transmit and receive backwards didn’t blow anything up.
about 8 months ago
All better now: the problem was that I’d left MEGA_SOFT_SPI turned on, which double-swizzled the pins when I used the Transmogri Sheild, making the SD not work. The CC3000 library has its own SPI library, which doesn’t seem to support soft SPI, so the Wifi was happy with the Transmogri shield.
For Arduino Mega 2560 rev 3 + the MicroSD shield, the MEGA_SOFT_SPI solution works great for me.
For Arduino Mega 2560 rev 3 + the CC3000 Wifi Shield, I found it better to put a Transmogri Shield between the Mega 2560 and the CC3000 Shield, and leave the SD library untouched (left MEGA_SOFT_SPI as 0)
Thanks for your help - works great!
The Transmogri Shield gives me good news and bad news: the good news is that my Sparkfun Wifi CC3000 Shield wifi works great with my Arduino Mega 2560 with a Triansmogri Shield in between (which was what I wanted to do in the first place: wifi + SD). The bad news is that with the Aruindo Mega 2560, the Transmogri Sheid,, the SD card on the Wifi shield doesn’t seem to work, using either the stock SD library or the Sparkfun SD library with MEGA_SOFT_SPI turned on: The WebClientSD example fails to initialize the SD card. I think too many wires are being swizzled by too many things.
Fortunately, I have several things to try out yet - I’ll let you know how it goes.
about 9 months ago
I have a question: to make the shield work with Arduino Mega 2560, could I make some hardware changes instead of modifying the SD library? From the schematic, it looks like it might work if I use some sort of headers to connect the Arduino Mega 2560’s ICSP pins to the shield ICSP holes, then cut the shield’s pins 11, 12, and 13.
I think if I make these changes I should then be able to use the standard SD library, with pinMode(8, OUTPUT) and SD.begin(8) in my sketch.
Is that correct? What headers should I use? Do you have headers that will plug into the ICSP 2x3 pins and extend them through the shield so I can do the same trick on a second, stacked shield?
Had to make some changes to make the shield work with Arduino Mega 2560.
1) In the SD library, in file Sd2Card.h, change MEGA_SOFT_SPI to 1 (rather than 0).
2) As described in the documentation, set pinMode(8, OUTPUT) and call SD.begin(8).
The change to MEGA_SOFT_SPI makes the SD library use pins 11, 12, and 13. The pinMode and SD.begin changes make the SD library use the required pin 8. I didn’t have to make the recommended changes to pin 53 or pinMode(10, OUTPUT).
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