Fail to pair more than one device

[Henry Wong]

Hello,

I tested nRF51822 with ble_app_hids_keyboard example, i found it cannot pair with more than one devices.

Procedures:

1. Pair PCA10001 with iPhone#1, it can be paired and connected.
2. Turn off Bluetooth of iPhone#1 and try to pair PCA10001 with iPhone#2. Although the name of HID keyboard can be scanned but it cannot be paired.
3. Reset PCA10001 and try to pair with iPhone#2 again, pairing is succeed.

Sometimes in step 2, I can pair and connect iPhone#2 after several times of trial, but it cannot work properly (fail to send char) and give out an error "NRF_ERROR_FORBIDDEN". I don't know the reason? The default Max number of bonded master is 4 and I have not edited it.

How can I pair a new phone successfully without reseting the nRF51822?

Thanks.

[Ole Morten]

When the keyboard application has been bonded with something, it will advertise with whitelist first, with a 30 s timeout. As long as it uses the whitelist, it will not be connectable for other devices, giving the behavior you describe. However, after this 30 s timeout, new devices should be able to connect.

If you always want to be connectable with new devices, you should not use whitelisting, but this might not always give desirable behavior. You should therefore take some care to make sure you cover the use cases you want.

[Jamie]

Hi Ole,

Can you elaborate more on what you mean above by, "If you always want to be connectable with new devices, you should not use whitelisting, but this might not always give desirable behavior." What undesirable behavior might arise?

Thanks, Jamie

[Ole Morten]

Unfortunately, I can't quite remember what I thought when I wrote that... :-P

However, my best guess is that my point was that if you always are open to receive connections from all Central devices, you may be connected to by a Central you don't actually want to be connected to. So depending on how you intend your device to be used, you should put some thought into these problems, and make sure that things work as you want to.