OK, we build 5 prototypes and tested them for the last 5 days and this is the recap:
1. DDR3 memory is working correctly – check
2. NAND flash is working correctly – check
3. PMU is working correctly – check
4. A13 is running perfectly, overall the board consumption is about 1W in idle and 2W at intensive computing. The chip have large 6×6 mm metal heat dessimation pad which we connecto to large ground planes on the PCB.
What we measure is that running at 1 Ghz A13 increase it’s temperature just 2C above the ambient temperature.
This was immediately exploted by Dimitar Gamishev who reported that A13 could be overclock up to 1.5GHz🙂
Generally with this heatsink eLQFP package is better for dissipating heat than A10 BGA package.
Of course this was done just out of couriousity we target industrial application and temperatures and overclocking is not recommended for normal operations. – check
5. Audio is working perfectly – check
6. Real Time Clock – works as expected – check
7. SD card works correctly – check
8. USB – works perfectly, there was minor issue with the GL850 hub, it have over current protection feedback with R58/R63 which in loop with the 4 capacitors was driving GL850 to oscilate the 5V power supply, generally this duplicate the SY6280 function, so we will remove it in the next revision.
We tested with Keyboards, Mouses, 3G modems and all they work correctly, Android have support for over 30+ 3G modems from different vendors build in, – check
9. Video – this is where we spent most of our time trying different configurations. As you know A13 have no VGA output, so we cheat it by creating simple resistor ladder Video DAC taking the LCD RGB, H-V sync pulses. We spent one whole day until we got the proper parameters set and we learned that A13 video controller pixel clock can’t go higher than 36Mhz.
This was confirmed by Allwinner later (this is part of the fun to work with processor without proper datasheet and user manual), so the maximum resolution we could squizee out of A13 LCD interface is 800×600 @75fps , well not perfect but – check
10. buttons: work fine, volume up down, home, back, power down/up and reset are all in good order – check
So overall we tested almost all features and they work fine, what remains untested: camera interface, GPIOs, SPI, I2C.
– A13 library component is not well done, I guess our developers used some of the standard Eagle QFP library with only 5.7 mils between the pads, this caused lot of shorts when the IC was soldered, we will increase the space between the pads to 8 mils for the next revision.
– Ground and Power planes stack-up was designed wrong in the first prototypes, we will switch them for the next revision.
So the conclusion: the first prototypes are success and work very good as for first attempt to route 1066Mhz DDR3 memory bus🙂