SparkFun Forums

[slide]

Im developing an application that requires very low power consumption. Does the nRF24L01 have any kind of wake-on-signal feature? I have a circuit that can generate about 0.6V when it is within range of the signal, but thats not that great for a pic, so id have to do some optimizing to get better. Any ideas?

[brennen]

Assuming you leave the 24L01 in power-up mode (PWR_UP bit in CONFIG register set), you can constantly receive messages. Assuming you want the device to wake up your PIC when it receives a packet, you can set the 24L01 up to reflect a packet reception to the IRQ pin. You would then wire the IRQ pin to an external interrupt pin on your PIC, and this would allow you to wake up the PIC on the change of that pin.

However, if you're just looking to basically get an RSSI (received signal strength indicator) signal out of the 24L01 to wake up your PIC, you're out of luck. It will only interrupt on packet receive, packet transmit, and maximum packet retransmission. You could theoretically wake up your PIC every so often and read the CD (carrier detect) register in the 24L01, which is 1 if a signal is detected in-band and 0 if not. That's about as close as you get to RSSI with the 24L01.

[RonnyM]

I am using a 16F690 with the 24L01 in a low power mode. It wakes from time to time, looks for a valid packet, then goes back to sleep if none is detected.
Standby power is around 3 uA. I run the processor at 31KHz for the wake up and check for transmission function. If a packet is received, I switch over to the 8 MHz internal oscillator and do the requested task.
The down side to this approach is that the transmitter will have to be on for more than one sleep period in order to make sure the receiver will hear it.

Ron

[jasonharper]

I have a circuit that can generate about 0.6V when it is within range of the signal, but thats not that great for a pic,

Why do you say that? Most modern PICs have at least one comparator with an adjustable voltage reference, which can easily detect a 0.6V signal and wake the PIC from sleep.