PICAXE Input Pin Types

[hippy]

TTL ( Vsupply > 4.5V )

Vih : >= 2.0V
Vil : <= 0.8V

TTL ( Vsupply <= 4.5V )

Vih : >= 0.25 * Vsupply + 0.8V
Vil : <= 0.15 * Vsupply

Schmitt Trigger (ST)

Vih : >= 0.8 * Vsupply ( >= 4V @ 5V )
Vil : <= 0.2 * Vsupply ( <= 1V @ 5V )


PICAXE-08 ( 12F629 )

Serial In TTL

In 1 TTL
In 2 ST
In 3 TTL
In 4 TTL

Vsupply = 2.2V to 5.5V ( 4MHz )


PICAXE-08M ( 12F683 )

Serial In TTL

In 1 TTL
In 2 ST
In 3 TTL
In 4 TTL

Vsupply = 2.0V to 5.5V ( 4MHz, 8MHz )


PICAXE-08M2

Serial In TTL

C.1 TTL
C.2 ST
C.3 TTL
C.4 TTL
C.5 TTL

Vsupply = 2.3V to 5.5V ( 4MHz, 8MHz, 16MHz )
Vsupply = 2.5V to 5.5V ( 32MHz )


PICAXE-14M ( 16F684 )

Serial In TTL

In 0 TTL
In 1 TTL
In 2 TTL
In 3 TTL
In 4 TTL

Vsupply = 2.0V to 5.5V ( 4MHz, 8MHz )


PICAXE-14M2 ( Preliminary Information )

Serial In TTL

B.0 Output - C.0 TTL/ST - Configurable by 'inputtype'
B.1 TTL/ST - C.1 TTL/ST
B.2 TTL/ST - C.2 TTL/ST
B.3 TTL/ST - C.3 TTL/ST
B.4 TTL/ST - C.4 TTL/ST
B.5 TTL/ST

Vsupply = 1.8V to 5.5V ( 4MHz, 8MHz, 16MHz )
Vsupply = 2.5V to 5.5V ( 32MHz )


PICAXE-18 ( 16F627A )

Serial In ST

In 0 ST
In 1 ST
In 2 ST
In 6 ST
In 7 ST

Vsupply = 3.0V to 5.5V ( 4MHz )


PICAXE-18A / PICAXE-18M ( 16F819 )

Serial In ST

In 0 TTL
In 1 TTL
In 2 TTL
In 6 ST
In 7 ST

Vsupply = 4.0V to 5.5V ( 4MHz, 8MHz )


PICAXE-18M2 ( Preliminary Information )

Serial In TTL

B.0 TTL - C.0 TTL
B.1 TTL - C.1 TTL
B.2 TTL - C.2 TTL
B.3 TTL
B.4 TTL - C.4 TTL
B.5 TTL - C.5 TTL
B.6 TTL - C.6 TTL
B.7 TTL - C.7 TTL

Vsupply = 1.8V to 5.5V ( 4MHz, 8MHz, 16MHz )
Vsupply = 2.3V to 5.5V ( 32MHz )


PICAXE-18X ( 16F88 )

Serial In ST

In 0 TTL
In 1 TTL
In 2 TTL
In 6 ST
In 7 ST

Vsupply = 4.0V to 5.5V ( 4MHz, 8MHz )


PICAXE-20M ( 16F677 )

Serial In TTL

In 0 TTL
In 1 ST
In 2 ST
In 3 ST
In 4 ST
In 5 ST
In 6 TTL
In 7 TTL

Vsupply = 2.0V to 5.5V ( 4MHz, 8MHz )


PICAXE-20M2 ( Preliminary Information )

Serial In TTL

B.0 TTL/ST - C.0 TTL/ST - Configurable by 'inputtype'
B.1 TTL/ST - C.1 TTL/ST
B.2 TTL/ST - C.2 TTL/ST
B.3 TTL/ST - C.3 TTL/ST
B.4 TTL/ST - C.4 TTL/ST
B.5 TTL/ST - C.5 TTL/ST
B.6 TTL/ST - C.6 TTL/ST
B.7 TTL/ST - C.7 TTL/ST

Vsupply = 1.8V to 5.5V ( 4MHz, 8MHz, 16MHz )
Vsupply = 2.5V to 5.5V ( 32MHz )


PICAXE-20X2 ( 18F14K22 )

Serial In TTL

C.0 TTL - B.0 TTL - A.0 TTL
C.1 ST - B.1 TTL
C.2 ST - B.2 ST
C.3 ST - B.3 ST
C.4 ST - B.4 ST
C.5 ST - B.5 TTL
C.6 TTL - B.6 TTL
C.7 TTL - B.7 TTL

Vsupply = 1.8V to 3.6V ( DC to 20MHz )
Vsupply = 2.7V to 5.5V ( DC to 64MHz )


PICAXE-28 / PICAXE-28A ( 16F872 )

Serial In ST

In 0 ST
In 1 ST
In 2 ST
In 3 ST
In 4 ST
In 5 ST
In 6 ST
In 7 ST

Vsupply = 4.0V to 5.5V ( DC to 20MHz )


PICAXE-28X ( 16F873A )

Serial In ST

In 0 ST - PortA 0 TTL
In 1 ST - PortA 1 TTL
In 2 ST - PortA 2 TTL
In 3 ST - PortA 3 TTL
In 4 ST
In 5 ST
In 6 ST
In 7 ST

Vsupply = 4.0V to 5.5V ( DC to 20MHz )


PICAXE-28X1 ( 16F886 )

Serial In TTL

In 0 ST - PortA 0 TTL
In 1 ST - PortA 1 TTL
In 2 ST - PortA 2 TTL
In 3 ST - PortA 3 TTL
In 4 ST
In 5 ST
In 6 ST
In 7 ST

Vsupply = 2.0V to 5.5V ( DC to 8MHz, internal resonator )
Vsupply = 4.5V to 5.5V ( DC to 20MHz, external resonator )


PICAXE-28X2 ( 18F25K22, 18F2520, 18F25K20 )

18F25K22 = 28X2
18F2520 = 28X2-5V
18F25K20 = 28X2-3V

Serial In ST

C.0 ST - B.0 TTL - A.0 TTL
C.1 ST - B.1 TTL - A.1 TTL
C.2 ST - B.2 TTL - A.2 TTL
C.3 ST - B.3 TTL - A.3 TTL
C.4 ST - B.4 TTL
C.5 ST - B.5 TTL
C.6 ST - B.6 TTL
C.7 ST - B.7 TTL

Vsupply = 4.2V to 5.5V ( DC to 40MHz ) (5V voltage version)
Vsupply = 1.8V to 3.6V ( DC to 64MHz ) (3V voltage version)


PICAXE-40X ( 16F874A )

Serial In ST

In 0 TTL - PortC 0 ST - PortA 0 TTL
In 1 TTL - PortC 1 ST - PortA 1 TTL
In 2 TTL - PortC 2 ST - PortA 2 TTL
In 3 TTL - PortC 3 ST - PortA 3 TTL
In 4 TTL - PortC 4 ST
In 5 TTL - PortC 5 ST
In 6 TTL - PortC 6 ST
In 7 TTL - PortC 7 ST

Vsupply = 4.0V to 5.5V ( DC to 20MHz )


PICAXE-40X1 ( 16F887 )

Serial In TTL

In 0 TTL - PortC 0 ST - PortA 0 TTL
In 1 TTL - PortC 1 ST - PortA 1 TTL
In 2 TTL - PortC 2 ST - PortA 2 TTL
In 3 TTL - PortC 3 ST - PortA 3 TTL
In 4 TTL - PortC 4 ST
In 5 TTL - PortC 5 ST
In 6 TTL - PortC 6 ST
In 7 TTL - PortC 7 ST

Vsupply = 2.0V to 5.5V ( DC to 8MHz, internal resonator )
Vsupply = 4.5V to 5.5V ( DC to 20MHz, external resonator )


PICAXE-40X2 ( 18F45K22, 18F4520, 18F45K20 )

18F45K22 = 40X2
18F4520 = 40X2-5V
18F45K20 = 40X2-3V

Serial In ST

D.0 ST - C.0 ST - B.0 TTL - A.0 TTL
D.1 ST - C.1 ST - B.1 TTL - A.1 TTL
D.2 ST - C.2 ST - B.2 TTL - A.2 TTL
D.3 ST - C.3 ST - B.3 TTL - A.3 TTL
D.4 ST - C.4 ST - B.4 TTL
D.5 ST - C.5 ST - B.5 TTL - A.5 ST
D.6 ST - C.6 ST - B.6 TTL - A.6 ST
D.7 ST - C.7 ST - B.7 TTL - A.7 ST

Vsupply = 4.2V to 5.5V ( DC to 40MHz ) (5V voltage version)
Vsupply = 1.8V to 3.6V ( DC to 64MHz ) (3V voltage version)

Serial In Summary

TTL = 08, 08M, 08M2, 14M, 18M2, 20M, 20X2, 28X1, 40X1

ST = 18, 18A, 18M, 18X, 28, 28A, 28X, 40X, 28X2-3V/5V, 40X2-3V/5V


Vsupply Summary

4.5V to 5.5V = 28X1 (16/20MHz), 40X1 (16/20MHz)
4.2V to 5.5V = 28X2-5V, 40X2-5V
4.0V to 5.5V = 18A, 18M, 18X, 28, 28A, 28X, 40X
3.0V to 5.5V = 18
2.7V to 5.5V = 20X2 (32/64MHz)
2.5V to 5.5V = 08M2 (32MHz)
2.3V to 5.5V = 08M2 (4/8/16MHz), 18M2 (32MHz)
2.2V to 5.5V = 08
2.0V to 5.5V = 08M, 14M, 20M, 28X1 (4/8MHz), 40X1 (4/8MHz)
1.8V to 5.5V = 18M2 (4/8/16MHz)
1.8V to 3.6V = 20X2, 28X2-3V, 40X2-3V ( 4/8/16MHz )

[Mycroft2152]

Great list!

[inglewoodpete]

hippy, can you add the 28X (16F873A) and 40X(16F874A)? Serial In and Port C inputs are all ST.

By coincidence, I found it out just this week. I am in the process of upgrading my current project from 28X (ST) to 40X1 (TTL) because I need the extra I/O and more programme space. I found my interrupts that worked on the 28X didn't interrupt on the 40X1. Luckily a small hardware mod overcame the problem.

[elf1564]

Excellent! Thanks for taking time to do this. I've copied and printed a hard copy for future reference.

Rusty Bates

[hippy]

Added the missing 28, 28A, 28X, 40X, 28X2 and 40X2 parts, and also added information about Vsupply.

[lbenson]

Just to clarify, in the Vsupply Summary, are you saying that, for instance, the 28X1 running at 4/8MHz wants a minumum of 2.0V (and should be reliable at or above that), but at 16/20MHz wants 4.5V to 5.5V?

Does this further imply that for, say, the 08M, the chip should be reliable running with DISABLEBOD down to 2V--below the approximately 3V at which Brown-Out Detection will turn the chip off? (That would say nothing, of course, about the viability of the rest of the circuit at 2V, or the risk that draw from a turned-on part could cause a dip below 2V.)

[Technical]

Just to clarify, in the Vsupply Summary, are you saying that, for instance, the 28X1 running at 4/8MHz wants a minumum of 2.0V (and should be reliable at or above that), but at 16/20MHz wants 4.5V to 5.5V?

Yes, that's what the official datasheets say. In practise you would probably get away with lower figures as the datasheet is quite conservative in it's figures.

Yes to second question too (28X1 also has internal BOD to watch out for). However it may 'operate' but not 'download' at lower voltages.

[hippy]

Many thanks to Technical for the corrections and filling in the missing pieces ( especially all the additional port pins for the X1's / X2's ).

Also to confirm that PICAXE's will often run lower than the minimum the datasheets state; I've run 18X's (4.0V-5.5V) at 3V3 without noticing any problems, but that doesn't mean it's always guaranteed. Best to use lower (4MHz) speeds when possible.

[BCJKiwi]

Re voltages.
Found that a 28X1 will download at low voltages (that's because it switches to 4MHz for the download - doesn't it?).
With setfreq em16 and an external resonator, it often starts at 4MHz if the voltage is anything around 4.25 or less - but sometimes it does start at 16MHz.

If started at 16Mhz on say 4.5V, it seems to keep running down to 3.5V (there is not a lot of load on it) but will switch back to 4MHz if reset while on low power.

[hippy]

Added PICAXE-20M to table.