6GHz+ Frequency Counter software important notes:

1) While writing this software, we discovered some bugs/incompatibilities in MMBasic. These have been addressed in updated firmware versions V5.04.08 and V5.04.09 beta. The HEX file supplied in this package uses the latest beta firmware (which is also included separately in this download package).

If you already purchased an Explore 100 kit or micro and it was supplied with the earlier V5.03 firmware, the software has been designed to work around these bugs as much as possible, so it should still work OK.

The problem fixed with the V5.04.09 beta release has to do with the drive signals to the 5-inch LCD panel. On our prototype, we experienced display corruption. The beta update of MMBasic fixed that. Only some proportion of LCD panels are affected, so if yours is not, you don't need to reflash your PIC chip. If you can't reflash your chip, you could try changing the .BAS file to run the CPU at 80MHz, rather than 100MHz. We suspect this should work OK (indeed we have done quite a bit of testing at 80MHz) but it's better to run at 100MHz if possible.

2) IMPORTANT - late testing led us to discover a problem with the BNC input circuitry which affects readings at higher frequencies. Therefore we recommend the following component changes:

a) remove the 100pF SMD capacitor connected to pin 25 of the Explore 100 I/O connector. This is directly to the right of diode D4, above and to the right of IC5.
b) solder a BAV99 SMD diode across the now empty pads provided for that capacitor, with its pin 1 close to IC6 and its pin 3 (middle pin) to the pad closest to the I/O header. Refer to this diagram for pin numbers:

    3
  [===]
   1 2

c) solder a 10pF ceramic disc capacitor between pin 25 of the I/O header and either adjacent pin 23 or pin 27 (both of which are connected to ground). Pin 25 is on the row closest to the edge of the board and above D10 (closer to its right side).

3) Some of the reference output functions had to be deleted to work around certain limitations of the PIC32 chip. The reference output can only be set to two modes: disabled or 1Hz pulses.

4) Writing to flash memory was found to cause inaccuracies in the frequency readings and so the software will not write to flash memory while measurements are underway. Settings are only saved either when you switch inputs (when the readings have to be reset anyway) or if you press on the "Save settings" text which appears on screen. If you press this, you will need to reset any averaging in progress or else the readings may not be accurate.
