Matrix user forums

As you may expect when using an 8 pin PIC I would like to have access to the gretest number of I/O pins. To do this I presumably need to use the internal 4Mhz clock and no MCLR.

As the Version 3 board is wired can I actually 'remove' the clock input?, I can go down to 1 pin with the R/C oscillator or would an option be to configure for the crystal oscillator and remove the crystal?

As for MCLR can I take it that the MCLR switch will simply act as an input switch when the PIC is not configured to use MCLR?

Any thoughts on the above will be welcome.

As an alternative I can use a PIC KIT 1 board for programming but my first thoughts are to stick with Dev Board 3 for ease of interface with Flowcode.

Hi Mark

Firstly your right about the reset switch acting like an input if the MCLR is disabled although i've not tested this idea on the Dev board.

As for the crystal oscillator changing to the internal oscillator will add I/O lines from your PIC aslong as the PIC is sat in connections that are going to switches / leds etc. If the pins are just wired straight to the oscillator circuitry then there is no point.

I'll add a note to this topic. You may have problems erasing a device that has been set to use an internal MCLR and an internal oscillator. If you have this problem, try switching the XTAL/RC switch on the board to the RC position.

Steve,

Thanks,

I have tested the use of MCLR as an input and it works fine.

Presumably the limitation of the oscillator pins not being readily usable even when configured as input/outputs is the same on the e-blocks processor board?

Hello Mark,

Yes, the same is true of the EB-006 multiprogrammer E-Block.

However, one solution for you may be to raise the 2 oscillator pins so that they don't go into the DIL socket and connect them to one of the free i/o lines (e.g. in one of the bigger DIL sockets). This would work for both the dev board and the multiprogrammer.

If you don't want to bend the pins of the chip, you could use another DIL socket or two between the chip and the DIL socket in the board, and bend the pins of one of these instead.