FlexRF module as actuator

[Nigel S]

I'm working on using the Flex module to control things and set it as Type7 as per the instructions using rf_config.py  Readback received from the module confirmed TYPE7.

My aim was to use the RELAYA (or GPIO) outputs on the Flex to actuate a high power external relay or other devices. 

However, when the Flex module is powered on the default output of RELAYA is high (3.3V), and the default outputs on the GPIO pins GPIOA,B&C are random.  GPIOC&A were High (3.3V) on initial power on, and GPIOB was indeterminate (1.5V).

Generally speaking the last thing you want after a power outage is for an Actuator to power on in the default RELAYAON or GPIO High condition.  I don't see a way to control this behavior via commands.  But as RELAYAON is always the default condition after power on, a workaround (for me) is to use an external high power relay that has the option to be OFF when the control signal is High (RELAYAON) and then use RELAYAOFF to turn ON the external relay.

I'm thinking this behavior is buried in the FLEX firmware and is not user controllable.

If anyone knows how to control it, I'd be grateful to know.

[Gadjet Nut]

Use a relay like this one that can turn a circuit on using either high or low:  

Alternatively ask JemRF kindly to update their firmware to have a configuration to default RELAYA/B either high or low on startup. 

On Mar 2, 2024, at 7:20 PM, Nigel S <nigel.s...@gmail.com> wrote:

I'm working on using the Flex module to control things and set it as Type7 as per the instructions using rf_config.py  Readback received from the module confirmed TYPE7.

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[Nigel S]

Thanks, that is exactly my set-up.  The photo was taken right after power-up before any commands.  One of the red leds on the relay shows the coil is energized out of the gate and the green-white circuit is closed.  As I'm using this to control my garage door opener so having this config would open my garage anytime after a power failure - not ideal :)  As you say, I can use the green-black circuit wired to my garage door opener so that failure mode doesn't happen, but as you can imagine if power get's cut to the relay but not the garage door then green-black goes closed, again opening the garage door.

I really can't think of anyway to use a relay for a job like this unless it's fed by a signal that is always low during power up and power down events so the coil is never energized unless Flex receives a command to go high.  Like you said I think only new firmware would make using a Flex module secure.

[Gadjet Nut]

Why do you have three wires on the right hand side? There should only be two. One of the pins will be low on startup and the other high. And they should share a common ground to the GND pin on the left. 

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[Nigel S]

Debugging.  testing with a multimeter to confirm both sides of the relay.  After installation only 2 will be connected to the garage door opening circuit.

[Gadjet Nut]

Then it’s something wrong with the wiring or the relay. The relay should be able to handle both high and low. 

On Mar 3, 2024, at 10:53 PM, Nigel S <nigel.s...@gmail.com> wrote:



Debugging.  testing with a multimeter to confirm both sides of the relay.  After installation only 2 will be connected to the garage door opening circuit.

On Sun, Mar 3, 2024 at 7:30 PM Gadjet Nut <gadj...@gmail.com> wrote:

Why do you have three wires on the right hand side? There should only be two. One of the pins will be low on startup and the other high. And they should share a common ground to the GND pin on the left. 

On Sun, Mar 3, 2024 at 7:16 PM Nigel S <nigel.s...@gmail.com> wrote:

Thanks, that is exactly my set-up.  The photo was taken right after power-up before any commands.  One of the red leds on the relay shows the coil is energized out of the gate and the green-white circuit is closed.  As I'm using this to control my garage door opener so having this config would open my garage anytime after a power failure - not ideal :)  As you say, I can use the green-black circuit wired to my garage door opener so that failure mode doesn't happen, but as you can imagine if power get's cut to the relay but not the garage door then green-black goes closed, again opening the garage door.

I really can't think of anyway to use a relay for a job like this unless it's fed by a signal that is always low during power up and power down events so the coil is never energized unless Flex receives a command to go high.  Like you said I think only new firmware would make using a Flex module secure.

<Flex Relay.jpg>

[Nigel S]

The relay is working perfectly as expected.  

Coil energized= green-white shorted, green-black open

Coil not energized =  green-white open, green-black shorted

Maybe I wasn't clear.  The relay is used to close a circuit emulating a button-push of the garage door opener.  The whole issue is that the Relay and GPIO pins on the FlexRF power up high which energizes the solenoid coil so my options are:

1. use green-white to actuate my garage door  --> Failure mode: garage door opens by itself after power restored when green-white is closed (security issue)

2. use green black to actuate my garage door -> Failure mode: if only the Flex module powers down but garage door opener is still powered, garage door opens by itself because green-black goes closed (security issue)

I think there's no solution other than the FlexRF module powering up with its o/p pins low so the solenoid is never  energized by any kind of power failure.

[Gadjet Nut]

The relay I have powers up low. 

On Mar 5, 2024, at 10:55 PM, Nigel S <nigel.s...@gmail.com> wrote:

The relay is working perfectly as expected.  

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[Gadjet Nut]

If the relay powers up low and the RF chip is wired correctly it will also power up the relay low. Try diagnose what’s causing the relay to go high on power up. 

On Mar 6, 2024, at 7:50 AM, Gadjet Nut <gadj...@gmail.com> wrote: