Fullscreen HTML5Med Res (??MB)HTML4

Programming a Micromite over Bluetooth In the September 2021 issue, Tom Hartley described how to connect an HC-05 device to a Micromite using an Android phone (siliconchip.au/ Article/15031). Tom's article made me realise that if I could get an HC-05 to work under TeraTerm, I could change my programs wirelessly. Many computers these days have built-in WiFi (including many desktops and virtually all portable computers). If they do, they usually have Bluetooth support as well. If not, you can get a USB Bluetooth adaptor for just a few dollars. Once you have a Windows computer with Bluetooth, you just need an HC-05 adaptor to program Micromites remotely! Under Windows 10, when an HC-05 Bluetooth device is detected, it creates two virtual COM ports. Windows 10 has drivers for the HC-05, so no drivers need to be installed. The great thing is that TeraTerm does not know the difference between virtual and real COM ports, so it works as if wires were connected. In Tom's article from September 2021, he describes how to attach the HC-05 to a USB-TTL serial converter to set it up. He mentioned that some HC-05 devices come without an enable button, but these may be set up to a baud rate of 38,400, so they may work without being set up. The devices I received had the enable button; they were set to 38,400 baud, but they still did not work without the setup procedure. Try to get the HC-05 that looks the same as the picture in Tom's article, with the tiny button on one side of the board close to the EN pin. Another thing to check is that there are six pins on the module. Setting up the module Set up the module using Tom's 98 Silicon Chip excellent instructions. He suggested powering the module from a 4.5V battery pack via a switch, but I used 3.3V from a CP2102 USB-TTL serial converter (Jaycar XC4464) via jumper wires. Plugging and unplugging the 3.3V jumper wire acts as a switch. We are not using USB to connect to the Micromite; the HC-05 has a serial output and connects directly to the serial input of the Micromite. If the Micromite has a USB connection, it must be disabled. For example, a Micromite LCD Backpack V3 can be configured for straight serial by removing the PIC16F1455 chip and connecting via the 5V/TX/RX/ GND header. Once you have followed Tom’s instructions to set up the HC-05, unplug it from the CP210x USB-toTTL serial converter and remove the CP210x from the computer USB port. Connect the HC-05 Tx pin to the Micromite’s Rx pin and vice versa. Connect the two GNDs together and the HC-05 Vcc to the Micromite’s 5V pin. Don’t connect the STATE or EN pins on the HC-05 module. The Micromite may be powered from any 5V source. The Micromite can now be several meters away from the Windows 10 computer, with no wires connected between them. Once the HC-05 is powered up (no need to press the button this time), go to the computer’s Bluetooth settings to pair with the HC-05. You should see a Bluetooth symbol next to the computer’s system clock, at the right end of the taskbar. If you can't see it, try pressing the ^ symbol. Click on the Bluetooth symbol and choose “Add a Bluetooth Device”. On the screen that pops up, click on the plus button next to “Add Bluetooth or other device” near the top of the window. You will get a menu Australia's electronics magazine titled “Add a device”. Choose the top option: “Bluetooth (Mice, keyboards, pens, or audio and other kinds of Bluetooth devices)”. You might see “HC-05” or “unknown device” appear, then the name should change to the name you gave it during set-up. Click on that and type 1234 in the password box that pops up. When the ‘paired’ notification pops up, click Done. Open Device Manager again and look under ports. You should see two new serial ports; mine were COM3 and COM6. I used the first one, COM3. In TeraTerm, use the File → New Connection menu option, set the Serial Port to COM3 (or whatever the first port in Device Manager was), then click OK. Set the terminal settings to how they should be to talk to a Micromite (in the Setup menu, click Terminal). That is, Local Echo off, Receive set to CR and Transmit set to CR. Now you are all set to program your Micromite. To test the connection, press Enter, and you should see the ">" prompt. You can type EDIT to access the full-screen editor or LIST to view the program. Note that if you have more than one HC-05, you have to remove one HC-05 from the Bluetooth setup window before you can communicate with the next one; at least, that was my experience. Now we have an HC-05 programmed to talk to the Micromite at 38,400 baud with the correct parity settings. It can be left attached to the Micromite board. You could put it in a project anywhere nearby and blissfully program away with nothing cluttering up the place except your computer! Grant Muir, Sockburn, New Zealand. ($75) siliconchip.com.au