I want to use the HM-10 as an iBeacon, but it would have to continuously advertise for 8+ hours a day. I know that the coin cell could power a HM-10 if used infrequently, but the module will not be put to sleep/low power mode - it is either on for a long time or off. I need to know if I am making the right decision to use a 3.7V ~500mAh LiPo to supply an iBeacon. Any advice?
Power Specs for HM-10:
Power: +2.5V~3.3VDC 50mA
Power: Active state 8.5mA; Sleep state 50~200uA
Another thing... It says it requires a current of 50mA but will only use up 8.5mA. What does this mean for battery life?
some test : an HM-10 (true one from Jinan Huamao) , configured as standalone iBeacon and powerered with a CR2032 battery is still running since april 2018 !!
Thanks for the info. I am intending to use this in a wristband, and the goal is to warn people if they are too close to someone for too long. It is a school project, and intended to be worn by everyone. The beacon will also relay UUID information to a scanner app made in MIT App Inventor, to have a sort of "track-and-trace" record if each UUID was assigned to a pupil/teacher. The app will also warn you if you are in a "close" radius for too long, vibrating the phone if you spend more than ~20 seconds within. The rough distance is obtained from the RSSI value.
I'm not sure I can allow a delay of 7 seconds to allow the device to work reliably. I was thinking that I could implement a power saving mode if the pupil was stationary. Would a coin cell still work in my case?
Well you can run beacons of a coin cell, but you cannot scan for beacons using a coin cell battery. You need to scan continuously to catch the beacon when it sends out the advertisement data, otherwise you might miss it.
You always need someone with a scanner. Two people with a beacon cannot be warned of being too close together. That is why smartphones are used for tracking people. When you have a smartphone, you do not need a wristband beacon anymore.
Klaus_K:
You always need someone with a scanner. Two people with a beacon cannot be warned of being too close together. That is why smartphones are used for tracking people.
That's precisely what I am doing - using the smartphone as a scanner for wearable iBeacons.
Klaus_K:
When you have a smartphone, you do not need a wristband beacon anymore.
Yes, track-and-trace apps are being developed to determine if you've been close to someone, but they are not reliable and have not been brought into mainstream use. That's why I want to use the HM-19 (HM-10 but Bluetooth 5.0 enabled instead of 4.0) - they are reliable, and it is easier to adjust phone behaviour relative to the module if the model of phone affects the results, rather than having several different phones that each behave in a different way having to adjust to each other.