Hello,
I'm running into some issues with my custom nrf52-based PCB
1. Random / Frequent connection timeouts. BLE disconnects every ~10 - 20 seconds. sometimes the connection stays longer.
2. Unreliable data transfers (i.e single data transfer taking longer than expected).
Initially, I thought these were Zephyr OS related, but I tried the ble_uart_app example using Segger embedded studio and the issues are still present. When I try using 2 Development Kits (PCA10040) the issues disappear, so I am convinced there is a hardware issue with my schematic / PCB.
Please can you take a look at my circuits and advice ?
I think I followed the proper copper pour and grounding rules for the antenna and oscillators.
BLE Settings: MTU Size: 240 bytes, Max Connection Interval: 40ms
Antenna: https://www.lcsc.com/product-detail/Antennas_Sunlord-SLDA52-2R540G-S1TF_C279814.html
32MHZ XTal: https://www.lcsc.com/product-detail/Crystals_Murata-Electronics-XRCGB32M000F1H01R0_C914155.html
32.768 KHZ: https://www.lcsc.com/product-detail/Crystals_Seiko-SC-20S-32-768kHz-20PPM-9pF_C97603.html
I have a few suspicions:
1. Antenna is too close to 32 MHz Xtal
2 Low Frequency 32 KHz clock is not properly isolated.
Please can you take a look and let me know if there's something I'm missing. I've never experienced this issue with my previous custom boards.
