Getting started with garage door project

Question

Hello 
 I am about to build a BLE central to open a motorized garage door (runs on solar power) with a smartphone. I am going to design a PCB for this. 
 However, I am an absolute beginner with BLE and I think I need a little help to get this started... There is a lot of information - too much. 
 First a bit more about the project: 
 
 I need some kind of security, so not everyone can connect and open the door. I thought about setting a passcode with a 4-digit push wheel or some jumpers on my PCB and then ask for the code when pairing. is there a name for this? Is there another way I should consider? 
 It should be possible to permanently pair about 8 phones. 
 
 What I did so far: 
 
 I bought the nRF52840 Dongle 
 Install SEGGER IDE 
 Try the blinky example from nRF5 SDK. 
 Read some tutorials, user guides and videos 
 
 Is there an example that is close to what I need? Can the nRF52840 be set up to be used with an external MCU (eg. STM32xxxx)? 
 I hope you can guide me in the right direction. 
 
 Kind regards 
 ProtonX

Andy · Answer

Hi ProtonX, 
 From what I read it sounds like you want to build a BLE peripheral, not a central. The phone would be the central in this case . 
 You can use a static passkey based on the jumpers on your PCB. Just search for "static passkey" in the DevZone and you'll find plenty of information. 
 I don't know if there are any examples close to what you need, but I'd advise you to get the BLE template project and build up on that. There's rarely an example project that exactly fits your needs. 
 I don't know what you mean with "using the nRF52840 with an external MCU". You can of course put both processors in the PCB and make them talk to one another over UART or so.