Active low transmitter question

[richard]

So how does this look for basic a Tx test loop?

wont work like you think , it will tx twice once as pin goes low then again as it goes high

Telemetry mode - Transmit (TX)
GAMMA module configured as a transmitter
Operation: When configured as a transmitter the GAMMA module will automatically default to
low power sleep mode. A change on any input(s) will cause the GAMMA to wake, read all inputs
and initiate RF transmission, (multiple input changes may take place simultaneously).

data sheet

[LEDave]

http://www.rfsolutions.co.uk/downloa...S-GAMMA-12.pdf

Ioannis / Richard - Hopefully I've uploaded a link to the RF Module (PDF was too large to upload directly).

It looks like there are two versions [Supply voltage Standard version 1.8 - 3.6 *V] & [Supply voltage high Voltage version “R” 3.6 - 16 *V]

Will post again this evening.

Ioannis - No email notifications received.

[LEDave]

Ok - So the transmitter will always Tx twice, on a button press to ground, then open contacts (if using a button). Or a transition from HIGH to LOW to High if using a pic GPIO pin to cause a Tx, correct?

From the data sheet:

'When configured as transmitter: Pins 3, 4, 7, 8, 9, 11, 12, 13 Inputs are internally pulled high, active low'

So no pullup needed. How about if I set a TRIS bit to INPUT, corresponding GPIO pin left open but GPIO pin connected to Tx pin 3 say which is internally pulled HIGH, active low. Then when I want to TX, switch the TRIS bit to OUTPUT and pull the corresponding GPIO pin LOW then switch the TRIS bit to INPUT again mimicking a button press.

Barking mad or genius?

[richard]

Barking mad or genius?

not genius yet

Inputs are internally pulled high, active low'

not that i can see, there is no active low, a tx occurs on state change
if tx telemetry mode engaged

you need to explain what mode you are employing and what you are trying to achieve

[LEDave]

Hi Richard

I got the idea of a Tx being initiated from the Data sheet 'When configured as transmitter: Pins 3, 4, 7, 8, 9, 11, 12, 13 Inputs are internally pulled high, active low'

But as you and Ioannis both say a Tx occurs on a pin state change. I assumed that if a pin changed from HIGH to LOW and stayed in the LOW state the transmitter would continue to transmit being 'active low' but my knowledge is very limited I'll be the first to admit but always keen to learn.

'you need to explain what mode you are employing and what you are trying to achieve'

In the short term all I'm aiming to do is to have an input into a pic from a sensor trigger a Tx, and the Rx via another pic to trigger an alarm.

Longer term, I'm fascinated by the idea of data transmission and would love to be able to configure a pic to transmit data - Set the Baud rate, SEROUT on Tx then SERIN and a lcd to read what's sent but that's for another day.

Right now just a simple sensor (beam gets broken) set off a Tx, Rx to trigger an alarm on receipt via another pic.

[LEDave]

So to make the transmitter Tx once only, the way to do it is just have one pin state change - High to Low or Low to High?

[richard]

beam gets broken set off a Tx , Rx to another pic a beam broken state.
beam gets restored set off a Tx , Rx to another pic a beam restored state.
the remote end always reflects the "beam" state
where is the problem ?
why the tx once only obsession ?

you might want to send a heartbeat to indicate tx link is active and working