STM32 MMDVM HS HAT Guide If using a new Raspberry Pi 4B, please remove the R1 resistor. STM32 MMDVM HS HAT Rev1.7 Guide Hardware enhancements (SDA, SCL): R20, R21 connect the STM32 I2C 2 bus to the OLED and Raspberry Pi. This allows OLED messages to display when powered on, even without the Raspberry Pi, using custom MMDVM_HS firmware and the I2C 2 bus. Supports I2C communication with Raspberry Pi. Settings for Pi-Star software and Raspberry Pi hardware (Raspberry Pi 0-3): If using a new Pi 4B, removal of the R1 resistor is necessary. Configuration Controller Mode: Simplex Node Radio Frequency: 144-148, 219-225 (Main Band), 420-475, 842-950 MHz Example Frequency: 438.000000 MHz Radio/Modem Type: STM32-DVM (GPIO) 14.7456 MHz TCXO with RXOFFSET=0, TXOFFSET=0 Quick Start Guide Download the image from here and write it to the SD card. Insert the card into the Raspberry Pi. Wait 5 minutes for booting and connect to Wi-Fi: Pi-star-setup (password: raspberry). Open http://pi-star/admin/ in a web browser. Set frequency, DMR ID, DMR mode, and add your home’s Wi-Fi SSID. Default Username: pi-starDefault Password: raspberry To Support I2C Communication Edit the MMDVM_HS code (by Andy Uribe CA6JAU) in Config.h: // Host communication selection: //#define STM32_USART1_HOST //#define STM32_USB_HOST #define STM32_I2C_HOST To disable I2C 2 to Raspberry Pi and OLED, simply remove R20, R21. Update Firmware Using Pi-Star / Expert / SSH Access (user: pi-star, pass: raspberry), run the following command: sudo pistar-mmdvmhshatflash hs_hat Note: Updating firmware removes the OLED power-on message. For more information, please visit www.mmdvm.club.
