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MAkse.1
MAkse.1
Visitor II
March 16, 2020
Question

STM32F103C8T6 and WS2812b

  • March 16, 2020
  • 1 reply
  • 1132 views

Hi everybody,

I'm complete noob and may be a silly question. But is it possible to connect WS2812b to a blue pill? As far as I know WS2812b hav 5V management logic and STM32 here gives 3.3V

What do you think? I've see someone did it, but no schemas or any other information :(

This topic has been closed for replies.

1 reply

KnarfB
KnarfB
Super User
March 16, 2020

You may check here: http://fabioangeletti.altervista.org/blog/stm32-interface-ws2812b/

For the ws2812b the data sheet says:

VDD +3.5~+5.3V

V_IH min. 0.7 VDD

So, for nominal voltage VDD=5.0V the GPIO high level must be 3.5V.

You have several options:

  • use a nominal VDD voltage which is lower (may insert a diode in 5V VDD path although this is wasting power and generating heat)
  • use a 5V tolerant GPIO in open-drain mode with an external pull-up R connected to VDD
  • use an external level shifter
  • do nothing special and hope that it works. It probably will for a prototype but you cannot do that in production mode.

Note that only the first input of a LED chain is affected.

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