I am currently working on a project where I was looking for a microcontroller that is capable of BLE (Bluetooth Low Energy) which determines a servo's position. Using an Arduino the project works well on a breadboard.

To have a better design of the project and enhance the energy efficiency (I need to use batteries and no breadboard) the Adafruit Trinket was recommended as once covered within this forum (For a 'customized' arduino consuming less energy making use of Attiny85 vs PCB Fabrication?). As I read I need to use the Adafruit Trinket Pro since the normal trinket with an attiny85 microcontroller will not enable me to attach a BLE module.

Researching on Trinket Pro 5V I found out that the onboard 5V regulator can provide only 150mA output and not 800mA unlike an Arduino Uno. Therefore I cannot attach the servo(250mAh/4,8V/6V) on the Trinket.

Now I was planning to make use of ONE battery box (6V) and attach it on the Pro Trinket, BLE Module and Servo. I don't see any other good solution given the requirement that I need to use only one 6V battery box. I am aware of the risk that the if the Servo uses too much current the device will not work anymore due to the lack of energy. However I will make use of Sleep and interrupt functions to increase the lifetime of the device.

Given the fact that I require a collaboration of a microcontroller, a BLE module and a servo motor, is there a way to use them together in a beneficial/recommendable way?? As of now I consider to attach all of them on an Adafruit Trinket Pro. However I guess I am thinking too naively; especially considering the battery requirement.

There was a similar question but I cannout extract a useful answer for me from the answers provided there (Using adafruit Flora or Adafruit Trinket + MPU-6050 3-Axis Gyroscope + nRF24L01+ together)

  • \$\begingroup\$ You can't find useful answers at the linked question because it wasn't a very good question. Same here. You can't get blood from a stone, and you seem to know that. \$\endgroup\$ Commented Aug 11, 2015 at 22:21
  • \$\begingroup\$ @Scott see my updated qustion...I hope to be more clear on my question nw \$\endgroup\$
    – Sathees
    Commented Aug 12, 2015 at 0:02
  • \$\begingroup\$ The ATtiny85 doesn't have a hardware USART. I hope you're ready for a little bit of pain in getting this working... \$\endgroup\$ Commented Aug 12, 2015 at 0:04
  • \$\begingroup\$ Don't mean to be rude, but PLEASE expand your acronyms at least once in your question. I didn't known what BLE was until I read the comments. \$\endgroup\$ Commented Aug 12, 2015 at 1:35
  • \$\begingroup\$ @IgnacioVazquez-Abrams the Adafruit trinket Pro contains an atmega 328 microcontroller and hence should have USART....you are definitely right that the normal Adafruit Trinket (attiny85) has no USART..therefore attaching BLE module would have been an issue with that one... \$\endgroup\$
    – Sathees
    Commented Aug 12, 2015 at 7:30

2 Answers 2


The Atmega328P can actually use a supply of up to 5.5V, so using a silicon rectifier to reduce the 6V and a bulk capacitor (after the diode) to help with brownouts will work, and the servo will be supplied directly off the 6V battery. If your BLE module needs 3.3V then you will have to use a separate regulator for that.

  • \$\begingroup\$ Thanks a lot...do you see any concern in this construction? \$\endgroup\$
    – Sathees
    Commented Aug 12, 2015 at 7:42
  • \$\begingroup\$ Make sure you don't use a Schottky diode by accident, since its forward voltage is too low for this. \$\endgroup\$ Commented Aug 12, 2015 at 7:43
  • \$\begingroup\$ Ok. Good to know. Is it ok to use a voltage regulator to make sure that the servo only works with 4,8V instead of 6V. Is this an advantageous approach? \$\endgroup\$
    – Sathees
    Commented Aug 12, 2015 at 7:45
  • \$\begingroup\$ Eh, if the servo works with 6V then it will reduce complexity and part count to connect it directly. Plus, the faster it moves, the shorter the brownouts will last. \$\endgroup\$ Commented Aug 12, 2015 at 7:47
  • \$\begingroup\$ so u mean it is preferable to connect it directly to a 6V battery box and let it work that way? \$\endgroup\$
    – Sathees
    Commented Aug 12, 2015 at 7:49

I am currently working on a project where I was looking for a microcontroller that is capable of BLE which determines a servo's position.

Cypress has microcontroller+BLE solution. Have a look, PRoC™ BLE (Bluetooth Smart)

Here is a link to datasheets

  • \$\begingroup\$ Thanks for your answer... On the link provided I cannot find any device ehere a microcontroler and a BLE module are attached together. I just had a look on the CYBL10X7X Family Datasheet... \$\endgroup\$
    – Sathees
    Commented Aug 12, 2015 at 7:47
  • \$\begingroup\$ There are two types PSoC and PRoC. Both are programmable and both has BLE on chip. Their IDE has graphical interface to configure the processor. these are the datasheets. cypress.com/file/137466/download \$\endgroup\$
    – Duresh
    Commented Aug 13, 2015 at 9:11

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