Custom Allwinner V3s boards


#1

Since many people are interested in building their own boards with the Allwinner V3s, I will start and show you my board.
My board will be used to read outputs from another device and then send the data over Ethernet to a server.
My board features USB Host / Ethernet / MIPI CSI / and many many inputs.
The inputs are read by an ATmega328, so the Allwinner V3s has a small Co processor.
My board won’t be publicly available and won’t be sold, so don’t be irritated by the open source hardware logo and the Allwinner V3s Dev-board text.

You are invited to show your custom boards aswell,

https://drive.google.com/open?id=0BwcliS5jl69cUW5zcHFQNDQ0TWM

PS: I really need to clean my pcb :sweat_smile:


#2

It is very difficult to tell just from a JPEG picture. I don(t know the exact purpose for this board and I just try to bring constructive remarks:

  • the power supply seems to be made up of LDOs only, which will be quite inefficient and probably dissipate a lot of heat
  • there is no ESD protection on the I/Os, USB, Ethernet, buttons, leds, etc.
  • what is the purpose of all these headers for “pullup/pulldowns”?

#3

Hi,
Nice work petit_miner. I am also planning to do my own board.
Can anyone suggest me a link to a good 3 channel DC - DC converter.
I will post once i am done with the board.


#4

If EA3036 not available, AXP203 is good choice.
But 1.8V (DDR2 power) will on а separate chip. sy8008/8009, mt3410, etc…
,


#5

EA3026 is not available. I am searching for a simple multichannel DC-DC converter. I am not getting one. May be i will have to use multiple single channel DC-DC converter.


#6

If area on pcb is enough, why no.
Your need, at least, four channels: +1.2 V , +1.8V, +3.3V, +3V.

+3V is analog power, LDO here is a good practic.


#7

My board uses ~150mA @ 12V (IDLE, and Ethernet plugged in)
On the back of the board is a DC DC Step down wich brings the 12V down to 5V.

With the Pullup Pulldown Header you can select wether the input is configured with a Pullup or Pulldown.

This is only a prototype so I wanted to keep things easy, but thanks I will add ESD Protection for the USB Port in the future.
I don’t think it is necessary for Ethernet?


#8

OK, so not so much power to dissipate.

You cén at least divide the number of pull-up / pull-down resistors by 2 by sharing a single resistor for both functions and tuing its other end either to VCC or GND.

As for ESD, for a professional board (not for a prototype), you have to add TVS to every externally-accessible connector / switch and LED (if not using light-pipes). In your case: the Ethernet and USB connectors, all screw connectors, and maybe the LEDs and push buttons.

And for both Ethernet and USB, you need to separate SHIELD from GND, with a single high-voltage (2 kV) 1206 capacitor to align both by shorting connection transcients.

Also, both Ethernet and USB signals being high-speed (480 Mbps and 100 Mbps, respectively), they need to be routed as a pair of differential signals with controlled trace impedance (90 ohms for USB, 100 ohms for Ethernet) and matched trace length, which does not appear to be the case.


#9

AXP203 seems also not easy to find, maybe AXP209, which looks very similar?


#10

AXP203 is available on Aliexpress.
But cost ~ 1$ . AXP209 ~0.3$ .

What differents.
AXP203: power-on DCDC3 output voltage is 3.3V.
AXP209: power-on DCDC3 output voltage is 1.2V.

DCDC3 may be programmed in ranges from 0.7 to 3.5 V, but system can not start with 1.2 V on I/O voltage and RTC voltage.

DCDC3 output may be used to DDR2 power.
In this case it must be programmed to 1.8V in SPL stage (using static memory).

+3.3V power on separate regulator, as on many Allwinner A13/A20 designs.


#11

Thank you @702, but where do you find this information?
In both AXP203 and AXP209 datasheets, same section 9.6, I see:
DC3SET PIN is used to set the initial voltage of DC-DC3:
DC3SET connected to GND : 1.8V
DC3SET connected to APS: 3.3V/2.5V
DC3SET floating: 1.2V/1.5V

Thus, in both AXP203 and AXP209, it seems that connecting DC3SET pin 29 to APS pin 21 will provide 3.3V on DC-DC3.


#12

Looks really good @petit_miner - have you tested the board? How well does it work?


#13

It works very good, in the next version I will change the LDO’'s to DC Step down inverters to save power and deliver more current. The LDO’s get really hot when the CPU is at 100% work.
At first I had problems with my Ethernet interface, because the link went up and down however I wasn’t able to recreate this error.
The USB Host doesn’t work anymore maybe I killed it with ESD?
There are still some issues that I have to investigate.


#14

You right.

Not clear, what mean “3.3V/2.5V”.

In “Typical application” (pg. 5) DC3SET is switched “GND<->VINT”.

“+1.8” variant is good, do not need programming.


#15

This board looks interesting. Have you separated the power supply of the digital and analog part ? Any spare bare boards ?


#16

I don’t know what you mean by seperated power supply :sweat_smile:
I used 4 LDO’s to create 3,3V 3V 1,8V and 1,2V, thats the easiest solution.
No this is a private project and won’t be published.


#17

My board doesn’t shutdown properly, it uses 140mA even after “poweroff” or “halt”.
It is the same amount of current when my board is operational.
Is it a bug or a “feature”??


#18

in https://github.com/Lichee-Pi/lichee-pi-zero/blob/master/HardWare/V3S/V3S_CDR_STD_V1_0_20150514.pdf (AllWinner Camera Dashboard Recorder Reference Design Schematics), they use the AXP203 with DC3SET pin connected to APS pin to get 3.3V on startup.


#19

Yes, it work in my experimental design.

Need to test AXP209 without change schematic.
Next time i’m try to solder AXP209 instead AXP203.

Variant “separate DDR power” is more preferable.
It need for “sleep mode”.


#20

Does the V3s support “suspend to RAM” mode using the DDR “autorefresh” feature?

This would be nice, as it would be possible to go to sleep consuming ~20mA and still wake up very quickly without having to reboot the Linux OS.