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by ag123
Wed May 24, 2017 10:06 am
Forum: Generic STM32F103
Topic: Blue pill and SD card
Replies: 5
Views: 65

Re: Blue pill and SD card

i think sd cards are fussy with voltage levels, in particular the vcc and ground supply voltages, 3.3v after a dropout LDO is possibly left around 2.2v, then *series* resistors probably distort signals in the mhz ranges, pull ups meeting the sd specs is ok. what may be attempted though is start with...
by ag123
Wed May 24, 2017 9:41 am
Forum: Generic STM32F103
Topic: Blue pill and SD card
Replies: 5
Views: 65

Re: Blue pill and SD card

get those without a level converter and without series resistors, pullups meeting the sd specs is ok, but series resistors probably make things worse by forming an RC circuit distorting the signals in the mhz ranges
http://www.ebay.com/sch/i.html?_from=R4 ... duino+3.3v
by ag123
Wed May 24, 2017 3:53 am
Forum: Generic STM32F103
Topic: USB Observations
Replies: 52
Views: 501

Re: USB Observations

hi all, kindly note that i've submitted a PR for hanyazou's and danieleff's fixes for inserting a short delay just after flashing the sketch http://www.stm32duino.com/viewtopic.php?f=28&t=2107#p28441 http://www.stm32duino.com/viewtopic.php?f=28&t=2107&start=10#p28452 kindly comment direc...
by ag123
Wed May 24, 2017 3:24 am
Forum: Generic STM32F103
Topic: USB Observations
Replies: 52
Views: 501

Re: USB Observations

i think it may be true that this is reproducible, my thoughts are that to diagnose this, it would be necessary to become familiar with the USB and USB CDC device class specifications. i'm not too sure if under certain conditions the host (i.e. PC / O/S etc) may end up in a *time out* due to an exces...
by ag123
Tue May 23, 2017 8:54 pm
Forum: General discussion
Topic: wrong serial boud rate
Replies: 6
Views: 60

Re: wrong serial boud rate

i think Serial.begin(115200) ^^^would be USB serial, or do you actually use Serial1.begin(115200); ? using Serial.begin(115200) would have no effect on Serial1 (HardwareSerial) as Serial = USBSerial the other things that isn't quite clear now is if this end is stm32f103 (e.g. blue pill) then what is...
by ag123
Tue May 23, 2017 1:17 pm
Forum: General discussion
Topic: Interfacing MPX4250AP
Replies: 7
Views: 73

Re: Interfacing MPX4250AP

i'm not sure about mpx4250, but i meddled with AD8232 https://www.sparkfun.com/products/12650 it seem analog voltages swing between 0-3.3v but leaving an offset between the bottom and top, e.g. somewhat higher than zero but somewhat lower than 4096, i'd guess it'd be quite safe creating a voltage di...
by ag123
Tue May 23, 2017 10:54 am
Forum: General discussion
Topic: Interfacing MPX4250AP
Replies: 7
Views: 73

Re: Interfacing MPX4250AP

do be wary that many of the ADC pins are not 5v tolerant
http://wiki.stm32duino.com/index.php?ti ... ini#Pinout
otherwise u may be taking chances with magic smoke production and short the stm32
but i'd think a voltage divider may work ;)
by ag123
Tue May 23, 2017 10:38 am
Forum: Generic STM32F103
Topic: USB Observations
Replies: 52
Views: 501

Re: USB Observations

@roger i'd think it is 'simplier' to leave USBSerial.begin() in the libmaple core initialization codes. the reason is that a lot of arduino sketches expect Serial to be 'there' and we'd likely get more 'complaints' about a non-functional Serial. using that 'flag' sounds like an interesting solution....
by ag123
Tue May 23, 2017 10:27 am
Forum: Generic STM32F103
Topic: USB Observations
Replies: 52
Views: 501

Re: USB Observations

@JohnO,
you have another device that's dfu capable hence the message, add the option -d 1eaf:0003 in the last line which installs the sketch itself

Code: Select all

#!/bin/bash
dfu-util -l
dfu-util -d 1eaf:0003 -a 2 -R -D $*
by ag123
Tue May 23, 2017 9:40 am
Forum: Generic STM32F103
Topic: USB Observations
Replies: 52
Views: 501

Re: USB Observations

i think delay(n) should never be called before serial.begin(), calling delay(n) before Serial.begin() can cause the *host* to time out and no longer recognise the usb device

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