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libretiny-eu / libretiny

PlatformIO development platform for IoT modules
http://docs.libretiny.eu/
MIT License
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instructions contradictory in ltchiptool? #270

Closed helgek closed 8 months ago

helgek commented 8 months ago

Hi,

when I tried to connect to the RTL8710B (so far unsuccessfully but I will try again with a better setup soon) these are the instructions shown in ltchiptool 4.11.1 (dev):

I: Found new device: ttyS4 - n/a I: Found new device: ttyUSB0 - USB2.0-Ser! - None (1A86/7523) I: Connect UART2 of the Realtek chip to the USB-TTL adapter: I: I: --------+ +--------------------- I: PC | | RTL8710B
I: --------+ +--------------------- I: RX | ------ | TX2 (Log_TX / PA30) I: TX | ------ | RX2 (Log_RX / PA29) I: | |
I: GND | ------ | GND
I: --------+ +--------------------- I:
I: Using a good, stable 3.3V power supply is crucial. Most flashing issues I: are caused by either voltage drops during intensive flash operations, I: or bad/loose wires. I:
I: The UART adapter's 3.3V power regulator is usually not enough. Instead, I: a regulated bench power supply, or a linear 1117-type regulator is recommended. I:
I: In order to flash the chip, you need to enable download mode. I: This is done by pulling CEN to GND briefly, while still keeping the TX2 pin I: connected to GND. I:
I: Do this, in order: I: - connect CEN to GND I: - connect TX2 to GND I: - release CEN from GND I: - release TX2 from GND

The part that I highlighted in bold letters is not mentioned at https://docs.libretiny.eu/docs/platform/realtek-ambz/#wiring and it also seems to not work together with the instructions in the paragraph following. Was this part of the instruction maybe inserted by mistake / not removed by mistake?

Thanks, Helge

kuba2k2 commented 8 months ago

The docs say:

This is done by resetting the chip while pulling down the TX2 pin.

ltchiptool says:

This is done by pulling CEN to GND briefly, while still keeping the TX2 pin connected to GND.

These two statements are equivalent:

as explained in the docs:

"CEN" pin is the RESET pin - connecting it to GND will keep the chip in "reset" state.

Unfortunately I don't have any ideas for better wording of the whole CEN/reset thing. People seem to not understand what that means, but I don't know a better way to phrase it.

helgek commented 8 months ago

The docs say:

This is done by resetting the chip while pulling down the TX2 pin.

ltchiptool says:

This is done by pulling CEN to GND briefly, while still keeping the TX2 pin connected to GND.

These two statements are equivalent:

* Pulling down = connecting to GND

* Resetting = pulling CEN to GND.

as explained in the docs:

"CEN" pin is the RESET pin - connecting it to GND will keep the chip in "reset" state.

Unfortunately I don't have any ideas for better wording of the whole CEN/reset thing. People seem to not understand what that means, but I don't know a better way to phrase it.

I think the ltchiptool formulation is good/better than the one in the docs. I just have problems to understand how

"This is done by pulling CEN to GND briefly, while still keeping the TX2 pin connected to GND."

is connected with

"Do this, in order:

Do these four steps try to explain in detail the sentence "This is done by pulling CEN to GND briefly, while still keeping the TX2 pin connected to GND." ? If yes then maybe the order of the steps is incorrect and should be (swap first and second step):

kuba2k2 commented 8 months ago

Indeed, the order is different than in the detailed sentence (the 1st and 2nd steps). But that doesn't matter - as long as CEN is released before TX2, it will work the same way.

helgek commented 8 months ago

That's right. The only thing that doesn't work in this order is to pull CEN to GND briefly. I don't know if this is relevant for this chipset but from your explanation I assume it's not. I think I saw some discussion before (don't remember which chipset it was about) where the duration of the CEN to GND was discussed, that's why I had assumed that "briefly" in your instruction might be of relevance.

kuba2k2 commented 8 months ago

No, it's not relevant. All that matters is for TX2 to be connected to GND while the chip powers up.

helgek commented 8 months ago

Thank you, I was now able to read the flash memory with an improved setup using a FT232RL based UART device ( https://www.amazon.de/dp/B07WX2DSVB?psc=1&ref=ppx_yo2ov_dt_b_product_details ) in connection with PCBite non-soldered connection. A bench power supply wasn't needed in my case to read the WR3.