Board’s arrived, now what?

So, your LPLC board has arrived. Great! It’s time to decide what to do with the header pins, and how to solder them. Bear in mind that you do not need to solder headers pins if you don’t want to, they are a convenience for connecting the LPLC to a breadboard or carrier PCB. In most cases you would solder wires directly to the PCB. The two long strips would normally be mounted underneath the PCB, with the sorter pins pushed up through the PCB. The programming header pins should be mounted vertically on the top of the PCB, or (as is our preference) soldered flat to the PCB. The following video shows how this is done.

 

The LPLC board comes with a bootloader program pre-loaded; This will allow you to transfer programs you create to the board without the use of a PCIKIT3 programmer device. To connect your board to your PC, you need to hook up a “TTL Serial to USB Cable” between it and you PC. These serial cables are very cheap, and readily available. Below is an example of how to connect the Olimex USB-Serial Cable-F, which you can buy direct from Olimex at this webpage. TTL Serial to USB cables can also be purchased on Ebay for a few Euros. An example for less than two Euros is here.

Here is an example of the wiring to the Olimex cable:

bootloader-wiring

 

Look below for articles on downloading the PC application, using the bootloader and more details on how the bootloader actually works.

Powering the board up

There are two ways to power the board: by , well, powering it up, or by plugging in a PICKIT3 programmer/debugger unit, and powering the board through that. It’s surprisingly convenient to use just the PCIKIT3, especially when you are travelling. If you are powering by batteries, we find two AA cell batteries in a small two cell battery holder works best during development. The board will run happily from two Alkaline, NiCad or NMiH batteries. No external regulator is required; just connect the batteries directly to the appropriate board pins ( GROUND and 3v3, as shown on the PCB layout drawing.) Powering via the PICKIT3 is even simpler. Just plug in the PICKIT3 as normal: Note how the PICKIT3 appears “upside down”. It’s not a problem; the LEDs on the top of the PICKIT3 are not really interesting. Only five of the six header pins are used, starting at pin1 (marked by a triangle on the top of the PICKIT3.) Plug the PICKIT3 into the PC, and start the MPLAB-X application. Click on the “Hold in Reset” icon, as shown in the figure below. Once the text in the lower “Output” dialog indicates that the PICKIT3 has connected to your board (“Target Detect”,) click the button again, and the board will power up. Please note: If you continue to use the board with the bootloader application, you should add a resistor ( a value between 4K7 and 50K) between pin 18, PORTC7, and 3.3V. This ensures that the bootloader does not start when you are running your board without a serial cable connected. This resistor is only required...

Using the Bootloader

The board is delivered pre-programmed with the Microchip Bootloader, a simple serial port based bootloader as described by the application note AN1310. The full download for the bootloader can be found on the Microchip website here. There are lots of files in there, and if you only want to use the bootloader you only need the user guide, the PC application and (possibly) the hex file for the LPLC. You can get those here: PIC18FBootloader To use them, download the zip file and then extract its contents into a directory, anywhere. I created a directory called C:\LPLC, and downloaded them there. The userguide is the pdf file 01310a.pdf. I found that userguide a bit confusing, so I will explain the use of the bootloader in – I hope! – clearer terms. Start by powering up the LPLC, connecting the USB serial cable to the PC and running the bootloader application, an1310ui.exe. You will see a dialog like this appear:   I’ve highlighted the three buttons of interest. When you first launch the program, you must click on the “Connect” button to connect the PC program to the LPLC board. We will come back to the other two buttons in a minute, because I am getting ahead of myself. The very first time that you start the program you must configure the settings: The comm port used by your serial cable, and the baud rate to use to connect to the board. The settings dialog is selected by clicking on the Program Icon followed by Settings. Choose the COM port number that matches your cable, and select the other options...

Self Assembly Instructions

Self Assembly If you are one of those crazy people enthusiasts who went for the ‘Self Assembly’ board option, here are the details for do the assembly. Click on the image to see a larger version:...

Memories of the first kickstarter

I found these images on my phone. Dimitry and I bagging up the first delivery of boards. The post office in Ireland are pretty cool, and when the local office got wind of what we were doing they handed us some official postal bags. Sadly, didn’t keep...