Another F103C8 board (but not good value)

Generic boards that are not Maple or Maple mini clones, and don't contain the additional USB reset hardware
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RogerClark
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Re: Another F103C8 board (but not good value)

Post by RogerClark » Mon Sep 18, 2017 5:51 am

I tried grounding the MOSI pin on a Blue Pill board (PA7) and also the RXD pin (Uart 1) PA9 but I always get an unrecognised USB device
( ground the pin prior to plugging in the USB)

I'll need to double check my board is not faulty, but at the moment it looks like the hex file you sent may be incomplete

I noticed 2 other people had downloaded it, but no one else has commented about whether it worked for them

Re: Crystal

Looks like its 8Mhz like the BluePill and most other F103 boards


BTW.
One other reason it may not work on the BluePill is often to stop people running the code on a different board, the code checks for another combination of pins always being pulled high or low or potentially a specific voltage on one of the ADC pins

But usually they also read-protect the code if they are concerned about it being re-used

flodejr
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Re: Another F103C8 board (but not good value)

Post by flodejr » Mon Sep 18, 2017 7:39 pm

Hi Roger,

I tried a different way of dumping the firmware. I used openocd and then via reset halt (I think these is the entry point. xPSR: 0x01000000 pc: 0x0800125c msp: 0x20001700) i did an image dump from 0x08000000 size 0x1ffff which yielded 128K dump image. Please see the attached.
usbfirmware.zip
128k bin dump
(14.14 KiB) Downloaded 9 times
I can see some text in the bin file like "Scanning for device 0 to 127", and some baud rates, I think the firmware is correct.

I have done also dump of the registers and disassembled the code via open ocd.
out.zip
registers and disassembly
(58.97 KiB) Downloaded 5 times

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RogerClark
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Re: Another F103C8 board (but not good value)

Post by RogerClark » Mon Sep 18, 2017 9:57 pm

Ok...

I will double check the BluePill I was testing with, does not have a hardware fault ( as they are prone to bad connections on the USB connector)
Then I will try your latest code dump


Thanks...

BTW.

I had a quick look on TaoBao to see if I could find the board listed, as sometimes they post more information to TaoBao than to eBay or AliExpress, but I could not find it, even then I translated the description to chinese using google translate.

There must be more information on this adaptor somewhere, e.g some sort of commands documentation, because I don't see how it could be useable for I2C otherwise..
I can just about understand how it could do Serial to SPI as long as it didnt have to use Chip Select, just by passing bytes to and from SPI to USB.
But some SPI devices require CS for synchronisation and framing.

flodejr
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Re: Another F103C8 board (but not good value)

Post by flodejr » Tue Sep 19, 2017 12:20 am

The board has a code CJMCU-308 on the bottom. I went to CJMCU's website but could find no such product. The closesi i can find is a FT232 to i2c/spi/uart, but its using the ft232's native capabilities.

I have tried almost all the software for similar adapters but none of them work.

Currently the board is in I2c mode and connected to a PCA9685. When I used arduino ide serial monitor, it is throwing scanning for device messages and displsying the i2c addtess of the 9685. However, when i key in anything to the serial, the messages will stop and the device will no longer respond.

I

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RogerClark
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Re: Another F103C8 board (but not good value)

Post by RogerClark » Tue Sep 19, 2017 12:36 am

I think you may be better off writing your own code to do whatever this board is supposed to do.

The only difference would be that you'd need to use a different USB driver as we don't have code that emulates the same USB to Serial adaptor.

But apart from that, I would have thought that writing code to transfer from USB Serial to I2C would not be too hard to write

flodejr
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Re: Another F103C8 board (but not good value)

Post by flodejr » Tue Sep 19, 2017 1:12 am

Yah worse case, i will just flash it into a bmp. Just that i paid premiun for the firmware and it doesnt work, i could have gotten 4 blue pills.

Anyway for the usb to i2c/spi/uart, there is already an opensource firmware littlewire that works on attiny digispark that cost $1.0

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RogerClark
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Re: Another F103C8 board (but not good value)

Post by RogerClark » Tue Sep 19, 2017 2:07 am

flodejr wrote:
Tue Sep 19, 2017 1:12 am
Yah worse case, i will just flash it into a bmp. Just that i paid premiun for the firmware and it doesnt work, i could have gotten 4 blue pills.

Anyway for the usb to i2c/spi/uart, there is already an opensource firmware littlewire that works on attiny digispark that cost $1.0
Thats always the gamble when buying from AliExpress of eBay (China), especially as most vendors don't include any docs in their listings, and even if they do include docs they can often be the incorrect e.g. for an entirely different board

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RogerClark
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Re: Another F103C8 board (but not good value)

Post by RogerClark » Tue Sep 19, 2017 2:45 am

I tried the latest firmware on a BluePill and it is now appearing as a CH340 is I ground pin PA7 (MOSI)

I'll try the other pin combinations later, but as there are no docs about how the I2C or SPI modes are supposed to work, e.g. can you send commands or just data, e.g. Enable SPI CS etc, then I think its going to be very hard to use this device for its intended purpose

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