Bluetooth Minidisc Remote

The Bluetooth Minidisc Remote will be a remote for portable Sony MD players that also transmits their audio over Bluetooth.

Status

• 2023-08-22: Started putting ideas together after getting back from a trip where I used a Bluetooth transmitter dongle connected to an RM-MC11EL a whole bunch.

Design Goals

• Same basic functionality you'd have on a regular Sony remote, though with an OLED screen
• Ability to remap buttons, if you want to use it with different portables or you want different controls in different places
• Ability to lock ("hold") all the controls except volume, since I've always wished remotes allowed this
• Bluetooth audio transmission to BT Classic endpoints (A2DP SBC)
• Ability to play/pause the MD device via the play/pause button on the Bluetooth receiver
• Transmitter will stop sending audio when nothing is playing (rather than sending silence like 3.5mm BT transmitters do)
• At least 8 hours of battery life on a charge hopefully (since with Bluetooth and an OLED, the remote will need its own internal battery)
• Custom 3D-printed enclosure that will hopefully not be that much bigger in L/W than the flat rectangular remotes for Kenwood portables, though will be a bit thicker because of the amount of stuff I'm trying to fit in

Design Overview

• Cypress 343026 module for MCU (built-in Cortex-M3) and Bluetooth Classic
• Fujitsu ELW2106AA OLED display
• DA7218 codec chip?
• Internal battery, charged via USB-C

Power Planning

Requirements:

• Input power
  • Li-poly pack, 3.0 - 4.2V
• OLED
  • OLED Drive - 15.5 - 17.5V (16.5V nom)
  • Logic - 1.65 - 3.5V (3V nom)
• BT/MCU
  • Logic - 2.3 - 3.6V (3.3V nom)
• Codec
  • Core - 1.7 - 2.65V
  • IO - 1.5 - 3.6V

Required rails:

• Logic - 3.0V (shut down when not connected to a MD device, fed via TLV62568 buck converter)
• Codec core - 1.8V (switchable, fed via second TLV62568 buck converter)
• OLED - 16.5V (switchable, fed via AP3012 boost converter)