Search found 106 matches

by chrismas9
Sat Mar 23, 2019 2:13 am
Forum: MicroPython pyboard
Topic: RTC Quartz datasheet available?
Replies: 8
Views: 498

Re: RTC Quartz datasheet available?

The 32 kHz crystal is sensitive to stray capacitance and also noise. The crystal requires 6pF load. Most of this (5pF) comes from stray capacitance - PCB and STM32. Only 1pF comes from the load capacitors. Any additional stray capacitance will affect frequency. Noise is also an issue. If you place a...
by chrismas9
Thu Mar 21, 2019 10:26 pm
Forum: Other Boards
Topic: [NUCLEO-H743ZI / STM32H743]
Replies: 4
Views: 449

Re: [NUCLEO-H743ZI / STM32H743]

What state is the boot pin in? Faint LEDs is often a sign that the STM32 started in bootloader mode because the bootloader enables weak pull-ups on a lot of pins, eg all the SPI ports.
by chrismas9
Thu Mar 21, 2019 10:06 pm
Forum: MicroPython pyboard
Topic: RTC Quartz datasheet available?
Replies: 8
Views: 498

Re: RTC Quartz datasheet available?

What is the very odd behaviour?
by chrismas9
Thu Mar 21, 2019 10:36 am
Forum: General Discussion and Questions
Topic: Filesystem size with custom STM32F7 build
Replies: 10
Views: 516

Re: Filesystem size with custom STM32F7 build

By default MicroPython only supports one continuous block of flash memory without holes in it. If you try to use multiple partial sectors, eg 64/128, then there will be 64k holes in the memory map (second half of the big sectors). Most ports use half of one big sector at the end. This is ok because ...
by chrismas9
Fri Feb 08, 2019 7:40 am
Forum: General Discussion and Questions
Topic: Terminology: upload vs download
Replies: 4
Views: 340

Re: Terminology: upload vs download

The most consistent use is on the Internet where upload and download are with respect to yourself. You always download a movie (to yourself) and upload a web page (from yourself) to a web server.

So you would download a log file from a pyboard and upload a new main.py to it.
by chrismas9
Sat Feb 02, 2019 12:10 am
Forum: MicroPython pyboard
Topic: CANbus bitrate and frame loss
Replies: 7
Views: 596

Re: CANbus bitrate and frame loss

This may not affect packet loss but I see two hardware issues that may affect reliability. There is no GND connection between the two devices on the bus. Without a GND you rely on the ESD clamp diodes to try and maintain the signals within the common mode range which is not reliable. There is no ter...
by chrismas9
Fri Feb 01, 2019 11:47 pm
Forum: General Discussion and Questions
Topic: Pyboard not working. Red, yellow and blue leds are shining.
Replies: 4
Views: 284

Re: Pyboard not working. Red, yellow and blue leds are shining.

Try the following: 1. Jumper P1 (Boot0) to X15 (3V3) 2. Plug USB into Windows computer. 3. You should get a ding ding noise if USB recognised. 4. Look in device manager. You should see STM32L4 device in DFU mode listed, probably under USB. If that works your STM32 chip and USB port are ok and you sh...
by chrismas9
Tue Jan 29, 2019 10:11 am
Forum: Other Boards
Topic: STM32F3 ports
Replies: 46
Views: 4528

Re: STM32F3 ports

IMO the F3 has been superceded by the F4 and L4. I would not start a new design around an F3. For similar price the F4 or L4 are faster, have more RAM and are better integrated. For example F3 needs 2 transistors and 6 resistors for USB. F4 needs 2 resistors. L4 needs nothing. There is not likely to...
by chrismas9
Tue Jan 22, 2019 12:53 pm
Forum: MicroPython pyboard
Topic: spi and chip select
Replies: 2
Views: 254

Re: spi and chip select

Yes, you can use any GPIO in SPI master mode and you can have multiple devices on same SPI buss each with their own GPIO CS. SS is only needed in slave mode where it is an input to the SPI block.
by chrismas9
Fri Jan 04, 2019 11:37 pm
Forum: MicroPython pyboard
Topic: PYBv1.1 V+ range
Replies: 7
Views: 557

Re: PYBv1.1 V+ range

All automotive systems suffer from alternator load dump which generates positive and negative spikes in the +/-60 to 80 V range. If the alternator is supplying 10A to the headlights and you turn them off the 10A keeps flowing, slowly reducing as the field current collapses. This causes the alternato...