How to connect DS18B20 and IR sensor to Axe020?

[taux3]

All inputs of the axe020 are pulled to Gnd via 10K resistors. Is there a way to bypass them to connect a DS18B20 one wire temp sensor and an IR TV remote control receiver (38Khz) ?

Regards
Antony
________
Honda SH125

 

[westaust55]

There is no way to bypass the 10k resistors.
You will need to carefully desolder and remove some resistors

 

[BeanieBots]

Agreed, and don't forget to add the pull-up resistor while you have the soldering iron in your hand.

 

[taux3]

chop it off ...

Axe 020 project board uses a 9 pin 8 resistors network in a sip package as pull down resistors for the input port. Assuming the side with the dot denotes the common ground of the network and also being in the edge of the PCB (the side with the dot), then by snipping the pin bellow the dot off disables the whole resistor network (i.e. disconnects it from Gnd).

Does it sound like a good idea?

Cheers
Antony
________
R60

 

[westaust55]

No because you will then be left with 10K resistors looping between the various PICAXE inputs. Effectively as 20kOhm between two inputs. and all still floating

If it is a Single in line package you may/will need to remove it entirely

 

[BeanieBots]

NO.
DON'T DO THAT.
It may well isolate it from ground, but then ALL your inputs would be influenced by ALL the other inputs.

If possible, just snip the one pin on the required input.

If not, remove the whole array, snip just the leg(s) on the inputs(s) required and then put it back.

 

[Technical]

The AXE022P board would be simpler to use for this type of setup.

 

[westaust55]

NO.
DON'T DO THAT.
It may well isolate it from ground, but then ALL your inputs would be influenced by ALL the other inputs.

Maybe I am just lucky then.

I use the AXE022 board as has just suggested above by Technical.

Other than where specifically required, by say a DS18B20 or a switch, I have no pull down/up resistors on spare inputs (digital or analogue) and do not suffer from problems.

 

[BeanieBots]

Out of context Westy.
My reply was to taux3, not you.
Our posts crossed.

 

[westaust55]

noted BB.

I guess as some further explanation for taux3:

It is not mandatory to have a pull down/up resistor for every input.
However, Rev Ed do suggest this approach to have the resistors.

Some members in the past have found that there interaction between analogue inputs if spare inputs are not pulled down to 0V.

 

[BCJKiwi]

The primary requirement is to have pullup or pulldown on all USED inputs, and for safety (as in eliminating spurious unexpected unfathomable activity) the secondary recommndation is to have them on ALL inputs.