Ok, you got me. I'm not wearing any boots.
The 1207 page datasheet is about enough to scare me back to xMega.
Design Goals :
- Powered by 2 AA batteries and a TPS60100 regulator.
- "Turns off" by going to sleep.
- 320x240 TFT LCD display with quick drawing. The whole reason to consider SAM vs xMega.
- Resistive touch screen.
- 2 5 way "navigation" buttons. Use one of these to turn it on.
- Micro SD card able to turn off by a PFET so it's not sucking amps while not used. It's "sleep" mode seems to be like a quarter milliamp. Used mainly for updating the software. Perhaps I should consider USB instead.
- SPI flash chip for holding configuration and settings. There may be lots of nonvolatile data.
- NRF24L01+ counterfeit for communication, 'cause it has to communicate with very cheap gadgets.
- Measure the battery voltage.
100 pin SAM4LS4CA-AU 'cause I kept running out of pins on the 64 pin xMega. So, what was I using ALL those pins for?
Use the SPI peripheral on PA21 through 24 for RF module and flash card
Use the SPI peripheral on PA27 through 30 for SD card so I can use RF module and Flash while SD card is turned off.
Use the 16 bit Port B for the 16 data lines to the display.
Maybe use C++ instead of C because I won't need __flash or memx.
Misc Questions (things I haven't yet found in TFM):
- In power down BACKUP mode, only the EIC lines can wake it up? I only find these on PA function C, so my SPI pins aren't on PA? Perhaps you switch the mux pin by pin?
- Can the ADC read voltages up the VCC instead of VCC-0.6 like the xMega? If not, then how 'bout connecting the DAC to the touch screen so I can set the "full scale" voltage. Maybe through a pair of pfets so I can disconnect the pin while measuring it. Can DAC drive enough current? Touch screens seem to be 330 ohms the short way and 660 ohms the long way. Could put an amplifier, but then I'd have to be able to turn THAT off too.
- PA2 selects Buck or LDO converter and needs to be high (or low) on reset. I should just connect this pin high and leave it alone? It's not like I have a shortage of pins.
- Perhaps some experienced user would say, "na, you want to do it THIS way instead. Save you much grief"?
More questions are sure to arise.