Replacing the STM32F103 on DSO138

[MathWizard]

I'm stiil fairly new to MCU's and especially STM32. I mangled up the pins on one of these LQFP48 packages years ago, and I have blank STM32F103c8t6's that I've used before, to make my own Bluepill copy on a protoboard.

I don't remember all the details, on what is required for setting up these chips. I used an Ardunio to upload programs to my blank STM32 chips, and I had the jumpers on there for programming modes, just like a Bluepill. I don't remember if I had to go setting fusebits or anything like that on 1st time use.

 Do I need to upload some bootloader first before uploading the scope program ? And can I do that on the DSO138 PCB with the serial com pins (and maybe a jumper adjustment) ? I gather that the USB port on the DSO138 is not supported in the scope's software, so I don't need to worry about some USB bootloader.

But I would like the ability to reprogram or update it at any time, maybe play with the code myself, doesn't that require some bootloader ?  Is the one already on it ?? I have a few programmer's like the TL48

[coromonadalix]

there's plenty of infos on how to / beginners  etc ... to fork your own bluepill, or any variations  you want

can be  a start

https://www.electronicshub.org/getting-started-with-stm32f103c8t6-blue-pill/

https://www.hackster.io/Shilleh/getting-started-with-stm32-blue-pill-in-arduino-ide-931b71

[ledtester]

Do I need to upload some bootloader first before uploading the scope program ?

From what I can tell, the STM32 System Memory Bootloader is pre-programmed by STM into a read-only memory on the mcu:

https://stm32world.com/wiki/STM32_Jump_to_System_Memory_Bootloader

https://stackoverflow.com/a/46077928/

And can I do that on the DSO138 PCB with the serial com pins (and maybe a jumper adjustment) ?

These instructions:

https://github.com/ardyesp/DLO-138#flash-binaries-directly-via-serial-interface

refer to a JYE document:

https://jyetech.com/wp-content/uploads/2018/07/dso138-firmware-upgrade.pdf

which shows how to connect a USB-TTL-UART to the DSO138.

[MathWizard]

Ok thanks, before I get to that I'm trying some mods I've read about. Like converting it to run off 5V, and modding the -5V rail, I'll have to scope that to make sure it's ok. Also decreasing the load resistors on the buffer, and moving the ground path for some cap.

I'm just looking at the front end, with it's TL084, and looking at it in LTSpice w/ a universal op-amp and adding some typical Vos and input bias currents (after turning the Rin way up), it can be quite a bit off for DC.

I have a second working DSO138, but I never used it enough to worry about the accuracy. I must test it and see if it's as bad as LTSpice says it could be, with for example -1.5mVos, and 12nA exiting both the op-amp's input nodes (those input currents might be off, or that op-amp was a fake).

Until I get a better handheld scope, I want to upgrade these for fun, and they can have the uses too, like repairing the stereo at a party, I'd be a hero.

[Sacodepatatas]

Ok thanks, before I get to that I'm trying some mods I've read about. Like converting it to run off 5V, and modding the -5V rail, I'll have to scope that to make sure it's ok. Also decreasing the load resistors on the buffer, and moving the ground path for some cap.

I'm just looking at the front end, with it's TL084, and looking at it in LTSpice w/ a universal op-amp and adding some typical Vos and input bias currents (after turning the Rin way up), it can be quite a bit off for DC.

I have a second working DSO138, but I never used it enough to worry about the accuracy. I must test it and see if it's as bad as LTSpice says it could be, with for example -1.5mVos, and 12nA exiting both the op-amp's input nodes (those input currents might be off, or that op-amp was a fake).

Until I get a better handheld scope, I want to upgrade these for fun, and they can have the uses too, like repairing the stereo at a party, I'd be a hero.

Yes, all the DSO138 clones that I bought from AliExpress have a fake TL084 (it's a disguised LM324). Vout goes to GND, bad crossover distortion when measuring sinusoids, bad V/I offset at the inputs.. I'd replace the TL084 with a new one from a reliable supplier.