Wednesday, May 14, 2008

Bootloader v0 release and maybe boards for sale

I am considering selling the extra boards that I have right now. I have 15 boards that I have not soldered on, etc. I am thinking about selling these boards for $40 (fully assembled and tested). If you wanted the programmer board with a cable, that would probably be another $10. I haven't been able to successfully write a programmer program because my parallel port is messed up. I have one I think works, but I would have to either get another parallel port (not too expensive) or else let somebody else try it. If anyone would be interested in purchasing a board, I plan on burning in a bootloader program previous to shipping the board, which uses the RS-232 port to upload user programs. Please leave comments if you'd be interested in a board so I can gauge response to see if it's worth ordering the extra parts.

The on-chip bootloader is written in assembly (yuck) and lives in the highest page of flash (starts at address 0x3E00). It uses the UART to communicate to the program that was written for the PC in C# to get its data. The program was written with the potential to be expanded, but that framework hasn't been developed yet in order to get it done quickly.

The only rub with using the bootloader is that, unless you can time hitting the RESET button really well, you need to add a green-wire fix to allow the RTS line from the RS-232 port to control the RESET pin on the nRF24LU1. This is relatively easy, and I will put up a schematic and pictures if anybody were to need it.

On-Chip Bootloader
The bootloader was written to be compiled with AS31, which can be downloaded (with a special version of SDCC) here. The link to the .zip file containing the makefile, asm source file, and compiled hex file can be found here.

PC-Side Bootloader
The bootloader program on the PC-side was written in C# for Windows (Linux guys are on their own). This version was written with Visual Studio 2005 Professional, but it can also be compiled using Visual C# 2008 Express, which is a free download from here. The link to the .zip file containing the C# project, source files, and executable file can be found here.

Edit: I now have nRF24LU1 breakout boards for sale at!

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At May 28, 2008 at 7:29 AM , Blogger Victor Meldrew said...

what SPI programmer did you use to program the devices with the Bootloader Image? What SPI EEPROM does the device emulate ?

At May 28, 2008 at 8:31 AM , Blogger brennen said...

I developed my own programmer using a Philips LPC2148 (however the firmware I wrote is a little buggy, which is why I developed the bootloader). Most all SPI EEPROMs I've used are interfaced pretty much the same way, the only difference really being the actual command codes used. It's actually pretty trivial to interface if you can get the SPI and PROG pins to work.

At August 7, 2008 at 11:21 PM , Blogger Unknown said...


I have been ask to evaluate creating a wireless device to communicate with OBD II units on new cars.

Company I work with sells software to car dealers that sell 90,000 cars a month.

From what I have seen on this blog you would be very well qualified for such a project because :

1. You program Micochip wireless devices.
2. PC interface to the wireless unit would be written in C#.


Where are you located?

Clay Laird
(254) 386 7628

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