Lichee Pi Zero Camera support


#1

Hi, thanks for posting the links for Allwinner SDK. I briefly looked at the files, but was unable to find a demo program for the camera. Also is there host ISP tuning tools ?
In addition, wondered if the camera ISP and MJPEG encoder are V4L compatible ? For example, does MJPEG streamer runs natively or needs modifications ? Support for RTSP video streaming ?


#4

Yes, but it is a big TODO to transplant to mainline…
ISP: lichee/linux-3.4/drivers/media/video/sunxi-vfe/isp_cfg
V4L, h.264, mjpeg encode: camdriod/device/softwinner/common/hardware/camera
RTSP: frameworks/av/media/CedarX-Projects/CedarX/libstream


#5

Thanks, one more question. Looked at the schematic on the git and it seems that the PE port (CSI) is power with 3.3V. But many image sensors are interfaced with different voltages. Is that the final version you will be releasing or plan to have updates ?


#6

You mean the DVP CSI interface?
Image sensors have 3 voltages: Vcore, Vio, Vanalog.
The voltage on the interface is Vio, most of them is 1.8/2.8V, and compatible with 3.3V.
I have made a RGB2DVP module, but didn’t put on indiegogo.
If you are intersted in camera and have backed on indiegogo, I can send it(&OV2640&OV5647) for you together.


#7

Regarding OV5647, based on the datasheet: I/O: 1.7-3.0 V. Many image sensors used quite odd I/O voltages. I am not sure what RGB2DVP module offers, but in my opinion would be useful if potentially some PCB jumper pads can re-route VCC-PE0 and VCC-PE1 to proper voltage.
No, I haven’t yet baked on Indiegogo, still considering what boards I would need.


#8

1.7~3.0V is the standard voltage range.
The absolute maxium voltage is 4.5V for Vio.
And in fact, as a highspeed signal, the voltage will attenuated though the lines.
It will drop to less than 2.8V (as I saw in oscilloscope).

In the other hand, PE0 & PE1 is for DVP camera, what I provide is OV2640. (OV5647 is provided as MIPI camera )
OV2640’s Vio is 1.7~3.3V.

Don’t be worried about camera, they are robust enough :slight_smile:


#9

Lichee Pi Zero上OV2640 DVP接口的支持是官方SDK里的驱动吗?
sys_config.fex怎么修改?
另外,我想买Lichee Pi Zero+RGB转DVP CSI模块,但是没找到RGB转DVP CSI模块在哪买。


#10

Does the lichee pi zero support the Raspberry Pi Camera?
I would like to use my raspberry pi camera with my lichee pi.
Does version 1 or version 2 of the raspberry pi camera work with the lichee pi?


#11

支持的,但这个转接板只做了样板,并未贴片,有需要可在qq小窗我购买


#12

The physics interface is not same, and you have to solder pins one by one…


#13

Yes I know that, I will build an adapter board for that.
But does it work electrical?
IO Voltage?
and so on?


#14

Yes, It Works (Refer to Allwinner SDK).
I notified Raspberry Pi Camera is cheap enough (OV5647), I will modify the Dock and let it compatible with Raspberry Pi Camera interface


#15

No, 1.7~3.0V is the recommended operating range, out of which you will shorten device’s lifespan.
Absolute maximum is the range where you will permanently damage the device.

So, operating the OV5647 at 3.3V is not good design :worried:.

Most cameras have an AVDD of 2.8V, some 3.3V and few 2.5V.

For DVDD (core), it is either 1.2V, 1.5V or 1.8 V.

And for DOVDD (I/O), it is either 1.8V, 2.8V or wide range from 1.7V to 3.0V at least (only a few extend to 3.3V or even 3.6V).

Thus, you should absolutely provide a way to choose PE, as it is done in the AllWinner reference design! If you use 3.3V for DOVDD, you will damage them very quickly!

As for the attenuation you observe on the scope, it is probably due to the scope’s ADC antialiasing low-pass-filter, but it is not real. What is your scope analog bandwidth in MHz?

See attached charts:


#16

Agree, it would be great to have VCC-PE0 and VCC-PE1 selectable connection to existing 3V3 or 1V8 by moving/resoldering 0ohm resistor.


#17

But the OV5647 (The same camera as on the raspberry pi) uses the MIPI CSI interface, so it doesn’t do anything to change the supply of PE0 and PE1.
The MIPI CSI interface has an extra supply pin, but it only works from 3V and up.
Does this work with the OV5647?
Edit:
Does the OV5647 already work with the Lichee Pi zero?


#18

Interesting thread, and especially about the 3.3v for the OV5647.

On the RPi the camera supply is 3.3v, so I’m assuming the camera board has an onboard LDO? Anyone confirm that?


#19

Yes, the Rpi OV5647 camera board features 3x TPS799xx 200 mA LDOs:

  • AWU marking: 1.5V (corre)
  • AXZ marking: 3.0V (I/O)
  • AWX marking: 2.8V (analogs

it also features:

  • A 24MHz oscillator
  • a LED
  • 2x I2C pull-up resistors

#20

All pins, excluding i2c, are outputs -> V3s inputs.
Such connection is safe. Sensor is not will be damage.
I2C control signals are “open drain”, safe also.


#21

Actually NOT all are outputs, at least there is a CAM_CLK … Another issue is the LDOs drop voltage etc.


#22

I’m really confused, the data sheet of the OV5647 mentions so many voltage ranges, but which of them mentions the max. IO voltage (Data lines)? (Not the supply voltage of the IO port, thats solved by using the Raspberry PI Camera)