STM32F102 oscilloscope chip questions ? - Page 1
Forum section: electronics / general

author: MathWizard
author_rank: Super Contributor
timestamp: February 27, 2024, 02:03:24 pm
content: I have one of these $20 DSO's with a stm32f103c8t6, it might have been sold as with 50-100-200kHz BW. The only other chip on it is an op-amp. But I damaged the MCU years ago when soldering it. I got some new chips, but forget there's no external memory chip, so all the program must have been on the chip.The PCB had connections for UART, and I2C or something similar, and a USB header. So I'm assuming the firmware could be updated.But in that case, can I put a blank chip on the PCB, and somehow upload the whole program ? (if I find it online).Otherwise, I can put the chip on a breakout board and try something that way. I do have an Arduino and a BusPirate, but I don't know much programming yet (but I've done some).I do want one of these mini, 9V DSO's, besides the low bandwidth, they are as portable as a handheld DMM. If I wanted to, I could remake just about any of the ebay ones on a protoboard, and use and open program for it. Everything for the little LCD screen is on another PCB with headers, just waiting for MCU instructions. I guess all that LCD stuff is open source and out there to find.How much is there to these mini-DSO programs tho ? For a real 50/100/200kHz BW, what might they compare to in size and complexity ? How many pages of code might these be ?Again, this one only had 1 MCU, 1 quad op-amp, and the all-in-one LCD section. So it takes a bunch of samples, does some DSP in the chip, then outputs to the screen. And has some buttons for basic DSO settings like zoom and coupling.

author: ataradov
author_rank: Super Contributor
timestamp: February 27, 2024, 03:48:08 pm
content: This device can easily be reprogrammed in-circuit, but I don't think you will find the firmware. And trying too hard for $20 does not seem to be worth it.

author: mikerj
author_rank: Super Contributor
timestamp: February 27, 2024, 10:41:57 pm
content: If it's one of the JyeTech scopes (e.g. DSO-138) then the binaries may be available :https://jyetech.com/products/There are also various open source projects for these small scopes onGithubif you search for the model name.

author: DavidAlfa
author_rank: Super Contributor
timestamp: February 27, 2024, 10:53:19 pm
content: Do you still have the original stm32? Even if some pins broke, you could still hack it to read the original firmware

author: MathWizard
author_rank: Super Contributor
timestamp: February 28, 2024, 11:07:10 am
content: Yeah that's the name, DSO-138, I'm hoping I can just upload the whole thing unto the chip, over USB somehow. I have the original, and it's missing a few pins, I can't remember what ones, I think I cooked it with the soldering iron too.I need to read some tutorials on these MCU's, I guess IDK if firmware is any different than the program itself, besides update instructions. But all that should be on their webpage, thanks.

author: pcprogrammer
author_rank: Super Contributor
timestamp: February 28, 2024, 12:45:15 pm
content: Maybe you already have one but a cheapST-Link V2can be of help. The STM32F102 you mentioned in the title, as well as the STM32F103 don't support USB programming off the shelf. It can be programmed either via USART1 or SWD. This is where the ST-LINK V2 comes in. It works with the SWD and only needs two signal wires besides the power and ground.If it is the DSO-138 you have then schematics can be foundhere. It even has a header for the SWD connection.There is tons of information on the net about how the use the ST-Link V2 to upload the binary. Can be done with tools from ST or with openocd and probably other tools too.