stm32f103c8 or esp32 for a datalogger

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mrburnette
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Re: stm32f103c8 or esp32 for a datalogger

Post by mrburnette » Tue Jan 16, 2018 3:18 pm

aster wrote:
Tue Jan 16, 2018 8:50 am
a) You have to release the code, that means "do the internes stuff to keep the connection going" with yield() or delay(0) i have read that it is suggested every 200milliseconds to be very safe. Mandatory every 500

b) Ray i just discovered about the revision in esp32 but for now i think that the 3 euros less is not enough good: https://cdn.instructables.com/ORIG/FJP/ ... WQBOV7.pdf or maybe yes :roll:

c) By the way i meant that i will use both the bluepill and the esp01 which will be used with AT commands to do the turn on / shooting of the camera
a) I think you are off by an order of magnitude. My readings suggest 30mS with a necessity approaching 50mS.

b) You're doing the design and pricing the components. I cannot argue with that.

c) The serial communications grew up on the "AT" concept. If it works for you ... do it.


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Re: stm32f103c8 or esp32 for a datalogger

Post by aster » Wed Jan 17, 2018 1:17 am

mrburnette wrote:
Tue Jan 16, 2018 3:18 pm
a) I think you are off by an order of magnitude. My readings suggest 30mS with a necessity approaching 50mS.

Ray
To be honest i read it on instructables, not thebest source of information i would say :lol:

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Re: stm32f103c8 or esp32 for a datalogger

Post by mrburnette » Wed Jan 17, 2018 3:35 am

aster wrote:
Wed Jan 17, 2018 1:17 am
mrburnette wrote:
Tue Jan 16, 2018 3:18 pm
a) I think you are off by an order of magnitude. My readings suggest 30mS with a necessity approaching 50mS.

Ray
To be honest i read it on instructables, not thebest source of information i would say :lol:
I always hate to leave something "open" without providing a definitive reference:
http://arduino-esp8266.readthedocs.io/e ... and-delays

Summary quote:
Remember that there is a lot of code that needs to run on the chip besides the sketch when WiFi is connected. WiFi and TCP/IP libraries get a chance to handle any pending events each time the loop() function completes, OR when delay is called. If you have a loop somewhere in your sketch that takes a lot of time (>50ms) without calling delay, you might consider adding a call to delay function to keep the WiFi stack running smoothly.

There is also a yield() function which is equivalent to delay(0). The delayMicroseconds function, on the other hand, does not yield to other tasks, so using it for delays more than 20 milliseconds is not recommended.

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Re: stm32f103c8 or esp32 for a datalogger

Post by ag123 » Thu Jan 18, 2018 4:09 pm

if floating point matters, i think F407 or maybe F405 is probably a king of the hill :lol:
Dhrystone and Whetstone Benchmarks for stm32
viewtopic.php?f=3&t=76&start=160
^^ almost 500 Mflops done by pito with overclocks
i have that strange feeling that a F407 could literally compress and stream video into files on an sd card, normally that's the job for those Ghz large arm cores e.g. R Pi 3, but F407 may be able to do so if the image is rather small and frame rates isn't too high

OT the black F407VET boards are reaching rather interesting price points
running close to $10 a board (i think some including shipping)
https://www.aliexpress.com/w/wholesale- ... 7vet6.html

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Re: stm32f103c8 or esp32 for a datalogger

Post by mrburnette » Thu Jan 18, 2018 4:28 pm

ag123 wrote:
Thu Jan 18, 2018 4:09 pm
if floating point matters, i think F407 or maybe F405 is probably a king of the hill :lol:
Dhrystone and Whetstone Benchmarks for stm32
viewtopic.php?f=3&t=76&start=160
^^ almost 500 Mflops done by pito with overclocks

OT the black F407VET boards are reaching rather interesting price points
running close to $10 a board (i think some including shipping)
https://www.aliexpress.com/w/wholesale- ... 7vet6.html
$10 per board is still 500% more than the cost of a < $2 blue board. Op is not building a quad-copter, just some data logging and a few sensors and possibly a future WiFi interface.

If we could get the F407VET down to $4.00 then I think the ~2x price differential would sway most of us to pay the extra for low quantity needs.
However, since the Op ultimately wants to have WiFi, an < $5 ESP32 board definitely should be considered for the future as that solution offers a very close price point to the F407VET, simplifies the hardware design, provides full coverage of the current known requirements; however, there is likely the port requirement for the desired libraries.

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Re: stm32f103c8 or esp32 for a datalogger

Post by ag123 » Thu Jan 18, 2018 4:34 pm

i think u're giving me some incentive to try out esp32 too :lol:
https://www.aliexpress.com/wholesale?ca ... Text=esp32
earlier on some of my searches seemed to land me on somewhat pricier esp32 boards

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Re: stm32f103c8 or esp32 for a datalogger

Post by mrburnette » Thu Jan 18, 2018 5:19 pm

ag123 wrote:
Thu Jan 18, 2018 4:34 pm
i think u're giving me some incentive to try out esp32 too :lol:
https://www.aliexpress.com/wholesale?ca ... Text=esp32
earlier on some of my searches seemed to land me on somewhat pricier esp32 boards
You will pay a little extra for the ESP32 boards with the "tin shields" covering the ESP32 + EEPROM as this configuration is RF/Noise reducing. Just for playing and DIY projects, the strict FCC stuff is not too important since most of what you can mess-up from digital harmonics is on your own home ;)
(maybe an ESP32 cluster could even warm up your lunch like a microwave over)

On the positive side, it makes the EEPROM easy to change. :lol:


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Re: stm32f103c8 or esp32 for a datalogger

Post by aster » Fri Jan 19, 2018 2:52 pm

$10 per board is still 500% more than the cost of a < $2 blue board. Op is not building a quad-copter, just some data logging and a few sensors and possibly a future WiFi interface.
yep, the f103 is enough for this

there is likely the port requirement for the desired libraries.
i already have the code compiling on esp32, maybe it won't work, who knows, but this is a good starting point :D

ag123 wrote:
Thu Jan 18, 2018 4:34 pm
i think u're giving me some incentive to try out esp32 too :lol:
https://www.aliexpress.com/wholesale?ca ... Text=esp32
earlier on some of my searches seemed to land me on somewhat pricier esp32 boards
he gave the same incentive to me too :lol:
when i will receive the esp32 i will decide which mcu to use and then make the pcb, the only problem is that i will see it in 2 months ahahah in italy the national post is soooo slow
i was just looking for the esp32's spi pins andddd them are configurable as you wish, "like a fpga", interesting :roll:

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Re: stm32f103c8 or esp32 for a datalogger

Post by mrburnette » Fri Jan 19, 2018 3:22 pm

aster wrote:
Fri Jan 19, 2018 2:52 pm
...
he gave the same incentive to me too :lol:
when i will receive the esp32 i will decide which mcu to use and then make the pcb, the only problem is that i will see it in 2 months ahahah in italy the national post is soooo slow
i was just looking for the esp32's spi pins andddd them are configurable as you wish, "like a fpga", interesting :roll:
Wish you were closer, I have 5 of the boards, 1 "real dev boards" and 4 clones. The clones were far less expensive, but we're slower to arrive. Adafruit has the official boards in-stock for $15 USD.... pricy but I wanted one "official" board just in case I had an issue with a clone.

There is one issue I have noticed with the Chinese boards that is not s/w or Espressif h/w but is a board layout and will not affect development:
https://www.hackster.io/rayburne/esp32- ... one-7f4ff7


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Re: stm32f103c8 or esp32 for a datalogger

Post by ag123 » Fri Jan 19, 2018 3:30 pm

aster wrote:
Fri Jan 19, 2018 2:52 pm
he gave the same incentive to me too :lol:
when i will receive the esp32 i will decide which mcu to use and then make the pcb, the only problem is that i will see it in 2 months ahahah in italy the national post is soooo slow
i was just looking for the esp32's spi pins andddd them are configurable as you wish, "like a fpga", interesting :roll:
the notion of a $4.90 board with wifi + ble + 32 bits (512k ram i think and running at some 200mhz?) is hard to match even for that wifi + ble + 32 bits alone, doubt it is easy to find something cheaper with the same. for ble there is nrf51822 but similarly those boards hover around $4 i think and is possibly slower than esp32 as nrf51822 is a cortex-m0 if i remember correct

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