If the Raspberry fails to connect the hotspot board, please try update the firmware of the hotspot board by conducting the command: sudo pistar-mmdvmhshatflash hs_hat-12mhz
Features
High efficiency, less power comsumption, High quality TCXO, stable, low BER
Support Raspberry Pi 3B, 3B +, Pi ZERO, with NanoPi NEO, Orange Pi, with BlueDV (requires USBtoTTL or Bluetooth model)
Support MMDVM mode DMR / YSF / P25 / NXDN / DSTAR / POCSAG
Support online upgrade, User-friendly OLED and Nextion special design location, reserved for additional installation of Bluetooth modules

Package List
1x MMDVM motherboard(UHF/VHF)MMDVM hotspot board supports UHF VHF, frequency range: 144MHz-148MHz, 420MHz-475MHz, 842MHz-950MHz (depending on ADF7021 and TCXO, HAT firmware amateur radio brand license restrictions)
Wide Compatibility: Hotspot radio board supports mmdvm_hs hat,mmdvm_hs dual hat and mmdvm modem rpt hat(oled display is not for now)
Support Bluedv: USB Hat board supports bluedv windows, bluedv-android, bluedv-ios, bluedv-linux DSTAR | DSTAR,DMR,Fusion(YSF, FCS)(only DN mode)
Muliti Functions: MMDVM Board supports mmdvmhost/mmdvmcal on linux/windows to test the mmdvm hat BER/DMR/TX check TCXO offset | BER XX%
Driver issue: Manual installation of the driver is required due to a discrepancy in the chip's PID. Kindly refer to the installation steps illustrated in the image. For any other issues, please us