Re: STM32F103RET6 and HSI

2022-08-25 Thread James Dougherty
HI Alan, Yes, that is true, some are really good - SAME70 will work that way but no USB. And yes, MEMS is not there yet. In this case, my BOM was wrong - X1 DNP - so I got enough running to make progress anyhow (tested a lot of HW). The most interesting aspect of this F103 finding for me is that

Re: STM32F103RET6 and HSI

2022-08-23 Thread Alan Carvalho de Assis
I don't know how ST internal oscillator is implemented in silicon, but some MCUs have good internal oscillator. For example the SAMD21 used on Arduino M0 board works fine with NSH running at 115200 and it even supports USB console, but I didn't test your freezing spray, maybe it could fail too. :-

Re: STM32F103RET6 and HSI

2022-08-23 Thread James Dougherty
Hi David, Wow. That is precisely what is wrong, you can get yourself a little TRIM and make one of the boards work, but then you would have to hand tune them +/- 1% for every baud rate and worse, temperatures. So better to pay the 71 cents and put the 8M crystal on the board. For testing I used co

Re: STM32F103RET6 and HSI

2022-08-22 Thread David Sidrane
HSI is not a good choice if there are external interfaces. It can vary too much part to part and over temperature to meet the 2% across the system boundary. They claim 1% @25c but that is 1/2 the budget to begin with, https://www.st.com/resource/en/application_note/dm00425536-how-to-optimize-stm32

STM32F103RET6 and HSI

2022-08-22 Thread James Dougherty
Anyone ever use the HSI on STM32F103, how about RET6? I know the code is set up for HSE. I got it working, at least UART1. But now, the other usart devices ... Wondering if anyone has ever run into UART baud rate mismatches on using HSI? I have a few radios that work great with an existing driver a