Something on F1C100s by piotr_go

piotr_go 14835 31

TL;DR

F1C100s experiments focus on a Chinese QFN88 SoC with ARM9, 32MB DDR1 RAM, LCD, camera, composite video, audio codec, touch, USB, SD, and DMA.
The setup uses a Lichee Pi Nano board and available interfaces to see what can be run from the system, with software taken from the linked download.
The chip's layout cost is approximately $2, making it an unusually cheap platform for embedded graphics and multimedia experimentation.
VGA at 640x480 already works through a converter board connected to the LCD connector.
The matching LCD touchscreen is still waiting to be brought up, and the final project goal remains undecided.

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#31 21252671 06 Oct 2024 14:11

cziter15 cziter15

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Post #31
21252671 06 Oct 2024 14:11

To avoid asking the author on PW, @piotr_go let me dig up the thread.

- How did you implement the RGBTTL? I'm mainly asking about the backlight - as far as I can see each display requires different voltages, as the rest, if I see correctly directly goes out to the FPC socket. This connector could be problematic from an RFI perspective. Do you happen to know anything more about the guts of the IC? Does driving the lcd set the slew rate accordingly?
- Assuming the use of CSI (camera), do you associate the possibility of a simultaneous LCD TTL? There perhaps one data pin is shared with the CSI pin. Does this mean either one or the other or is it possible to reconcile both peripherals?
- I'm thinking of some kind of signal conversion to TMDS, on the wallpaper I have SIL504CMG208 (I2S audio but here may be the problem the same as with CSI) and TFP410.

I'm asking purely hypothetically, I'm building projects as a hobby but I don't want to ignore any issues. It is not enough for me that somehow it works .

I originally wanted to make a remote control for some small vehicle on this IC. Assuming using a video codec and e.g. LTE on USB, it could theoretically push video there.

However, I decided to build some sort of breakout to protest both TV and LCD interfaces. I don't want a ready-made one either, as I intend to familiarise myself with the hardware.

Regards,
Krzysiek
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#32 21252755 06 Oct 2024 15:08

piotr_go piotr_go

DIY electronics designer

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Post #32
21252755 06 Oct 2024 15:08

cziter15 wrote:
I'm mainly asking about the backlight - from what I can see each display requires different voltages
.
Inverter with current stabilisation. I can change the measurement resistor if necessary.

cziter15 wrote:
Does the lcd drive the correct slew rate setting?
.
I don't recall any slew rate settings. Maybe they were cut from the PDF, maybe they weren't.

cziter15 wrote:
Assuming the use of CSI
.
The camera did not interest me at all.

I dealt with it over 4 years ago. I don't remember everything exactly anymore.
I was planning to switch to something newer (Cortex Ax) with more RAM so I let the F1C200s go.
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Topic summary

✨ The discussion revolves around the F1C100s, a Chinese System on Chip (SoC) featuring an ARM9 processor, 32MB DDR1 RAM, and various interfaces including LCD, camera input, and audio codec. Users are experimenting with the Lichee Pi Nano tile, exploring applications such as SDR receivers and HMI displays. The conversation includes technical insights on interfacing LCDs, using external ADCs for better performance, and developing software without a full operating system. There are mentions of the F1C200s model, which offers enhanced capabilities. Participants share progress on hardware and software development, including successful implementations of USB, DMA, and graphics widgets.
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FAQ

TL;DR: The F1C100s is a US$2 Allwinner SoC that bundles 32 MB DDR1, VGA/LCD, audio and USB; “the whole thing starts in less than a second” [Elektroda, piotr_go, #18643031; #18643646]. Why it matters: You can build sub-second-boot HMIs, handheld SDRs or retro-gaming tiles with minimal BOM.

Quick Facts

• Package: QFN-88, 10 × 10 mm [Elektroda, 18643031] • Integrated RAM: 32 MB DDR1 @ 133 MHz [Allwinner F1C100s Datasheet] • Core: ARM926EJ-S @ 400 MHz (no FPU) [Datasheet] • Typical cost: US$1.8–2.2 in 1k lots [Elektroda, post #18643031] • Video out: RGB-TTL up to 800×480; CVBS in/out supported [Datasheet]

What makes the F1C100s attractive for hobby projects?

It combines CPU, 32 MB RAM, LCD, audio, camera and SD in one low-cost chip, so you need only power, flash and a few passives to start a GUI project [Elektroda, piotr_go, post #18643031]

Does the F1C100s include a floating-point unit?

No. The ARM926EJ-S core lacks an FPU, which complicates real-time DSP; users aiming at SDR moved to the V3s Cortex-A7 with VFP [Elektroda, 18645296]

How do I flash code without JTAG?

Install sunxi-fel.
Hold or disconnect the SPI-flash so the ROM enters FEL mode.
Run “make flash” from the sample Makefile to push SPL and image via USB [Elektroda, 19037216]

Is there a ready "hello-world" project?

Yes. The archive linked in the first forum post contains minimal SPL, driver library and a C ‘hello world’ that runs from SRAM, useful for bare-metal starts [Elektroda, 19039228]

Can it run Linux?

Mainline Linux boots on the chip; boards like Lichee Pi Nano ship with it, but cold-boot takes 3–5 s and uses more RAM, which some projects avoid [Elektroda, 18769854]

What is the fastest observed bare-metal boot time?

Author reports <1 s from reset to GUI on his HMI demo, thanks to NOR flash and no OS layers [Elektroda, 18643646]

How do I bring up an 800×480 RGB-TTL LCD?

Wire LCD data lines to the SoC RGB pins and supply 3.3 V logic.
Drive the LED backlight with a constant-current boost inverter; adjust the sense resistor per panel [Elektroda, 21252755]
Program timing registers (HSYNC, VSYNC, PLL) per panel datasheet [Datasheet].

Can I capture composite video and show it on the LCD?

Yes, if you expose the CVBS pin block, understand its undocumented registers, and write a driver to DMA frames into LCD memory. "If you find a description of the CVBS registers and write the appropriate driver, why not." [Elektroda, piotr_go, post #20926914]

How to add better stereo ADC for SDR?

Use an external dual-channel 24-bit codec (e.g., PCM1802) on I²S; disable the internal mono ADC and clock the external part from MCLK. Forum users noted the built-in ADC tops at 48 kHz and one channel only [Elektroda, ArturAVS, post #18643842]

What differs between F1C100s and Allwinner V3s?

V3s swaps the ARM9 for a Cortex-A7 with VFP, doubles RAM to 64 MB, adds Ethernet MAC and comes in LQFP-128, making it drop-in for projects needing floating point and LAN [Elektroda, 18645296]

Any performance pitfalls?

Leaving the data cache disabled can slash frame-rate; enabling it raised Doom from low FPS to full-screen smooth play in the demo [Elektroda, 18660812]

What is typical power draw?

Bare-metal VGA demo measured ~200 mA @ 5 V including LCD backlight; SoC alone idles near 90 mA @ 1.2 V core and 3.3 V IO (Allwinner Power Table). An overload or short on backlight boost is a common failure edge-case.

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