STM32 + BLE module for super low energy application

Thread Starter

zazas321

Joined Nov 29, 2015
856
Hey. I would like to get some advice regarding the selection of the bluetooth module for the low power STM32 microcontroller. I also would like some general advice regarding the STM32 and bluetooth modules.

I need to send some data on my STM32 few times a day, therefore I thought the best selection would be the STM32L series since they have low power consumption.
I need to have BLE module connected to the STM32. The BLE is waiting for someone to connect and then it has to wake up the STM32.
I want to know:
1. For example if there are some external events that also need to wake up the STM32 such as movement detection. Is it better to wire this sensor to bluetooth module and once detected send wake up signal to the STM32? Since bluetooth module should always be ON (waiting for user to connect). Or is it better to connect the sensor straight to STM32 and somehow wake the microcontroller from low pow power mode when a movement is detected? Which one is more energy effiecient?

2.What BLE module would you advice me to use with the STM32. The only requirements are super low power usage and bluetooth 4.0 support.
 

Thread Starter

zazas321

Joined Nov 29, 2015
856
Mostly considering between CC254x or nRF bluetooth IC. Some bluetooth IC's require an additional microcontroller and some do not.

I am wondering which one is more power efficient? If a bluetooth module requires an additional microcontroller, does that mean that it relies on the external microcontroller to be powered ON? Can someone clarify this for me please? What exactly are the differences between the bluetooth IC that works independently and the bluetooth IC that needs external microcontroller?

I mainly need the external microcontroller to read some sensors, send data when it is waken up but I believe this could be accomplished with independant bluetooth IC since it has GPIOs. But I am not sure whether it has deep sleep funcionality GPIO wise to save as much energy as possible such as STM32L series ( being able to wake up thorugh the RTC interrupt every few hours or so, as well as external hardware interrupt)
 
I would consider to use the HC05 bluetooth module (or similar), it's cheap and easy to apply. I would power the bluetooth module only when it's required.
The system wake-up shall be designed according to your wish (e.g. the STM32 can wake-up by pin state change), the STM32 has a great low-power mode support.
Gabor
 

Thread Starter

zazas321

Joined Nov 29, 2015
856
Thanks for the response. Lately, I have been reading about new STM32WB devices and ordered a few development kits to play with. Since this is for production, I was not fully convinced that HC05 is the best choice for this project.

I had some good previous experiences with STM32 and their devices, however STM32WB does not seem to be very popular yet as there is quite limited information on the internet and very little people talk about it compared to other STM32 processors.
 

Santy1302

Joined May 26, 2021
2
Thanks for the response. Lately, I have been reading about new STM32WB devices and ordered a few development kits to play with. Since this is for production, I was not fully convinced that HC05 is the best choice for this project.

I had some good previous experiences with STM32 and their devices, however STM32WB does not seem to be very popular yet as there is quite limited information on the internet and very little people talk about it compared to other STM32 processors.
Hi, I am in a similar situation like yours. After doing lot of research, landed into stm32wb ..And I am about to order the dev kits. Can you share your experience about the stm32wb. whether it's possible to wakeup by bluetooth core cortexM0? And mainly what is the power consumption when in waiting for bt connection?
 

Thread Starter

zazas321

Joined Nov 29, 2015
856
Hello all. The project has been delayed so I have no answers to share unfortunately. If you find something interesting out please do share it!
 

Santy1302

Joined May 26, 2021
2
Hello all. The project has been delayed so I have no answers to share unfortunately. If you find something interesting out please do share it!
Hello all, After doing a little more research, Ti CC2540 board which is on top of HM-10 BLE board is having a 8051 microcontroller and there are some gpios left for the users. And with cc debugger we can program and debug this chip. For my application I just need some gpios and hope it solve my purpose. Also i believe it's possible to control another microcontroller by acting like master. Only little draw back is its ble 4.0 and stm32wb is ble5.2. But it's not bad compare to HC-05 which is bt 2.0..
 
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