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Note: This is my first real electronics project I've worked on by myself so I might just be asking a dumb question or this might be in the wrong forum. I am trying to figure out the hardware side of a project I'm working on so I thought this might be the best place.

I am working on a project that involves a Bluetooth module that I need to control some GPIO on a PCB. I have looked around a bit and found this module which states it has GPIO on many of its pins. In the manual it says it has a total of 17 pins that can be used as GPIO along with other functions, such as ADC, PWM, UART TXD and RXD, and many other things that I don't really need (although the PWM might be of use eventually). I have yet to buy the module because I am trying to figure out if this is indeed what I need before I buy it.

The problem I am facing is that I have no idea how you control or set these GPIO pins as the documentation says nothing about them. Of course it mentions the AT commands for Bluetooth, which I understand, but that pertains to general Bluetooth module settings like baud rate, name, MAC address, connection interval, etc.

How is this module actually used as a GPIO interface?

The documentation mentions it uses an ARM968E-S processor if that is of any use.

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  • \$\begingroup\$ It's a chip thing, not a module thing. The module just connects the GPIO pins to the processor chip's GPIO pins. Unfortunately the page doesn't say much about the chip. The processor documentation also isn't helpful because the GPIO is outside of the processor (it's the part of the chip that isn't the processor) \$\endgroup\$ Commented Sep 27, 2022 at 21:05
  • \$\begingroup\$ @user253751 Would it be best to contact Dreamlnk that makes the module? I can't imagine they would make a module that you couldn't use a large portion of its advertised functionality. \$\endgroup\$ Commented Sep 27, 2022 at 21:10
  • \$\begingroup\$ You could try . \$\endgroup\$ Commented Sep 27, 2022 at 21:11
  • \$\begingroup\$ I'll try that. If I get any updates I'll post them here just so that anyone with a similar question by chance can have an answer \$\endgroup\$ Commented Sep 27, 2022 at 21:12

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Getting access to the SDK for low-level programming of these Chinese modules is typically quite difficult. Nevertheless, you could give it a shot and email them at the address given on the last page from the device's Datasheet

I can anticipate that the SDK (most likely all in Chinese) and additional required hardware will make it more difficult.

I would rather use a conventional BT module, communicate with it via UART and delegate all of the IO duties to your Master MCU of choice (Arduino, STM, ESP-32, etc).

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  • \$\begingroup\$ I was looking for a while before I decided this module and couldn't find what I was looking for (maybe I don't know what to search), but do you have a recommended MCU that can simply do the DAC from UART to 8 or more GPIO pins? I am hoping to have my board fabbed by JLCPCB. I suppose it could be I2C as well \$\endgroup\$ Commented Sep 27, 2022 at 21:18
  • \$\begingroup\$ You can use virtually any BT module that has good documentation and plenty of examples online for you to understand better how to tackle your problem. Assuming that you are at a beginner-intermediate level, I would suggest using a ready-to-use solution, like the Feather BLE board from Adafruit. You mention that you will need to use a DAC, in which case you must wire up one externally (SPI or I2C). However, I don't know what you mean with the "...do the DAC from UART..." part \$\endgroup\$ Commented Sep 27, 2022 at 21:28
  • \$\begingroup\$ I think maybe my question now is what is the correct search terminology for the MCU that will take the output from the Bluetooth module (in UART, I2C or SPI) and convert it to 8 channels of analog GPIO output. That is just a DAC right? But DAC seems like a broad term and I still can't seem to find what I need \$\endgroup\$ Commented Sep 27, 2022 at 21:35
  • \$\begingroup\$ Actually I think I have found what I'm looking for. They would be called I/O Expanders I believe. I've been looking at JLCPCB for parts and this is what they call them. There are so many categories it just took a while to figure out what was the right one \$\endgroup\$ Commented Sep 27, 2022 at 21:40
  • \$\begingroup\$ Have a look at the MCP49XX family or at the DAC7611. I am focusing on SPI devices as they are considerably faster, however, an I2C might do the trick for you as well \$\endgroup\$ Commented Sep 27, 2022 at 21:41

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