PicAxe20M

[eagre]

I have been unable to find a datasheet for the PicAxe20M, covering all possible uses for its I/O pins. The "Datasheet" click on the 20M listing just goes to "manual1" which gives no such information, and AXE118 gives only defaultmpin assignments.

Ed

 

[hippy]

Not sure what you mean by "all possible uses for its I/O pins" but AXE118.PDF has all the details on pin configuration. The "default pin assignments" are what you have; inputs on the left, outputs on the right.

The 20M is based on the 16F677 - There may be some functions which are available which cannot be accesed using PICAXE Basic but can be through poking to SFR's, but that's going to be quite limited and I don't know of anyone who's experimented in that respect.

 

[westaust55]

Like Hippy,
Not sure what else you are looking for.

Datasheet AXE118 and PICAXE Manual 1 on page 6 both show the 20M.
The diagram shows the functionality of each pin as supported under the installed BASIC interpreter.

Sure some chips such as the 08M and the 40X1 have up to 4 or 5 possible functions per pin under PICAXE BASIC, but the 20M is relatively straight forward with most physical pins have just one function and others having two possible functions.

 

[eagre]

hippy and westaus55 -

Thanks for your replies. What I was looking for was something like manual1, Appendix C, which describes pin assignments for the PicAxe14M. There are other appendices for the 08Mand 28X1, but none for the 20M.

Ed

 

[hippy]

The 20M is 'fixed format' so no appendix for the 20M as nothing can change. The only specific dual-purpose functions are the INFRAIN and INFRAOUT connections and the ADC's.

 

[eagre]

Thanks hippy -

I had incorrectly assumed that the 20M was an extension, and improvement, of the 14M. This was because they were based on the closely related PIC 14p and 16p 16Fs.

I guess I'll stick with the 14M and get by with fewer I/O pins.

Ed

 

[westaust55]

Thanks hippy -

I had incorrectly assumed that the 20M was an extension, and improvement, of the 14M. This was because they were based on the closely related PIC 14p and 16p 16Fs.

I guess I'll stick with the 14M and get by with fewer I/O pins.

Ed

The 20M is still an "extension" of the 14M in that it has 2 extra Outputs, 3 extra Inputs, the Serial Out has its own pin (not shared) and there is possibility of 2 extra ADC inputs.

For just £0.10 or AUD$0.65 more to step up from the 14M to the 20M, I would have considered the 20M as the way to go.

It would cost more than the extra price (£0.10 or AUD$0.65) just to buy a single IO expander chip to get more IO. Then, as the 14M and 20M do not have i2c comms, use of an I2c IO expander is not an option.

While your latest words suggest that you may already have a 14M, then so be it, but if starting out I would recommend going the 20M route over the 14M for the extra IO. You may not need them initially but they may come to the fore at a later time.

 

[hippy]

The 20M and 14M are similar but different. Which is best depends on what you actually need. The 14M has the flexibility of control over "Port C" which the 20M doesn't and a few extra abilities the 20M doesn't have, the 20M is easier to use if happy with its I/O configuration and don't want to get involved in the complexities of using Port C.