HC-05 Module Setup - Githubissues

digitaldanny / AudioEffectsGlove

A hand tracking glove that controls parameters of various audio effects.

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HC-05 Module Setup #37

Closed digitaldanny closed 3 years ago

digitaldanny commented 3 years ago

Describe the solution you'd like

Wire up HC-05 module with the MSP432.
Basic SW drivers to read/write messages to the HC-05 via UART.
Test that data can be read/written to a desktop application. For example, this could be a very basic C# script that returns 'B' if the microcontroller sends 'A.'

Other relevant notes

Research for this issue was completed in #24.
Message protocol definition and connection/disconnection/encoding/decoding will be handled later in issue #35.

digitaldanny commented 3 years ago

2nd HC-05 module delivered. Picking up on Sunday (02/07).

digitaldanny commented 3 years ago

This GitHub repo may show how to interface the MSP432 and the HC-05 module.
This TI link is the Bluetooth SDK documentation that Shan sent me.

digitaldanny commented 3 years ago

TI MSP432 Baud Rate Calculator converts from expected baud rate to register configurations.

digitaldanny commented 3 years ago

Quick summary of the changes included in commit 1e1307e.

UART module configurations. Using P2.2 and P2.3 as UART Tx/Rx. Tested with 38400 baud rate in HC-05 cmd mode (EN pulled high).
Wired up P6.0 as an input GPIO for reading HC-05 STATE pin.
Unit test that sends out "AT+NAME\r\n" and can read data back. This unit test needs to be improved to compare returned data with expected return message "AT+NAME=HC-05." Currently, I was able to read back "TNM?\n" in the interrupt. I believe this is because a few bytes are received at a time, but I am only reading one byte per ISR handler.

digitaldanny commented 3 years ago

HC-05 Datasheet here

Realized today that the power rails were dipping with the HC-05 module connected. Although the datasheet says that the HC-05 module is powered with 3.3V, my breakout board includes a 5V to 3.3V regulator with a 300 mV dropout voltage. I believe I can just desolder the regulator and directly wire the 3.3V pin to the breakout board's power header.

digitaldanny commented 3 years ago

I tried desoldering the regulator and directly connecting the 3.3V power rail to the power pin on the breakout board (shown in the screenshot below), but I am still seeing a 64 mV power rail dip when the LED flashes.

HC-05 Rewire

64 mV Dip on 3.3V Power Rail

digitaldanny commented 3 years ago

I do not think there's any hardware dependent on an exect 3.3V power level, so I am going to continue working on other issues and come back to this if it looks like it's giving me problems.