Allwinner T113-S3 wont start

[XTEC]

Long shot... we have an Allwinner T133-S3 SoC, on our own custom board. This is an ARM version of the D1s (pretty much identical operation we're told). When we power on, the 24MHz oscillator starts but that's it... nothing else happens. No clock to the SD card looking for firmware, and USB does not come alive for the FEL.

We have a MangoPi, and when we 'scope that we do see it sends a clock to the SD card, and the USB does come alive upon boot.

We have checked all power rails, power start-up sequence and timing, the 24MHz oscillator looks good (~1v P-P sine), the BOOT_SEL pins are set for SD card boot, and we've basically checked every other thing we can think of. We followed all the guidelines given by Allwinner. We are at a loss. Oh, and we've tried 3 MCU's now!

I know this is almost impossible to answer, but does anyone have any brilliant suggestions as to what else to try?

[AVI-crak]

Allwinner chips are very demanding to the order of initialization of blocks and peripherals. There are a lot of cross-links in them, so it is almost impossible to start one of them. In the best case the chip will hang up waiting for the flags to be processed, in the worst case it will start consuming current until it burns out.
Hint: the cheapest Chinese stereos have accessible jtag (expensive models - no access).

[sd]

Shouldn't there be a resistor at DZQ to GND?

[darkspr1te]

I would check your reset is working correctly and also check the BOOT_MODE0 and BOOT_MODE1 pins status,


darkspr1te

[XTEC]

Shouldn't there be a resistor at DZQ to GND?

Yes there should be. I had missed that on the PCB design, but added by hand. Still won't boot unfortunately.

[XTEC]

I would check your reset is working correctly and also check the BOOT_MODE0 and BOOT_MODE1 pins status,


darkspr1te

Reset seems to be correct. We've checked reset timing upon power on, and it's pretty much exactly as per the data sheet. We have about 100ms after supplies are stable before the reset goes high. We also checked power supply timing, and that's also per the data sheet.
We checked the BOOT_MODEx pins, and they also appear to be correct. We even tried adding pull-ups, to make sure they really are both high after boot. And according to data sheet, if no boot media is found, then we should enter FEL mode and the USB should be alive. We just have zip.

[sd]

Try connecting VCC-TVIN to 1.8V and VCC-TVOUT to 3.3V.

[XTEC]

Try connecting VCC-TVIN to 1.8V and VCC-TVOUT to 3.3V.

I will double check, but I think we also saw that mistake and hand soldered connections. But I will check we did that. Thank you!