Vrp mvp one frontside

VoLTE Retrofit Project Spanaway Hardware

Overview

This device, when finished, will act as the first piece of reference hardware for the VRP project. The device should be easily debuggable and handsolderable.

Hardware Overview

The device is a two PCB design with "front board" containg the interface, MCU, and audio circuity. The "rear board" will handle power and modem. Both boards will interface via two 8 pin dupont headers. An alphanumeric tranflective display and a matrix of tactile 6mm push buttons will act a the primary user interface. The device will continue to use a mini-pcie form factor modem. All audio will be routed through an I2S codec and a mux will be used to switch sources (between the MCU or Modem). A single cell Li-Ion battery will power everything.

Detailed Hardware Documentation

Audio

The Spanaway phone uses a TI TLV320AIC3104 audio codec. This codec supports I2S, has integrated pre-amps and a headphone power amplifier making it well suited for this application. A TI SN74CB3Q3257 is used to select which I2S device the codec communicates with, the choices being the MCU or the Modem. When not in a call, VOICE/MEDIA is pulled low selecting the MCU, durin a call this pin is pulled high selecting the codec. The MCU controls the coded via I2C selecting which inputs and outputs to use, this behaviour is defined on a per state basis.

DEVICE_STATE_IDLE

The handset is at "rest" during DEVICE_STATE_IDLE, all audio inputs and outputs are unsused/muted.

• MCU is selected (VOICE/MEDIA is low)

DEVICE_STATE_MEDIA

• MCU is selected (VOICE/MEDIA is low)
• audio inputs are unused (could change if audio recording is implemented)
• audio output may be earpiece or headpones

DEVICE_STATE_INCALL

• modem is selected (VOICE/MEDIA is high)
• audio inputs may be headset or integrated mic
• audio output may be earpiece or headpones

FRONT BOARD
	OVERVIEW
		Userfacing hardware like the display and button matrix along with the primary MCU and audio will be handled by this top board.	
	MAJOR COMPONENTS
		MICRCONTROLLER: ATASAMD21G18
		CODEC: TLV320AIC3104
		KEYPAD: disrcete micro switch buttons
		HEADPHONE JACK: SJ3-35094BG
		MICROPHONE: CMB-6544PF
		EAR PIECE SPEAKER: AST-01508MR-R
		BUZZER: CUI
		SPEAKER AMPLIFIER: TPA6203A1
		SD CARD HOLDER: MOLEX
		I2S MUX: SN74CB3Q3257
			
REAR BOARD

	MAJOR COMPONENTS
		MINI PCIE CONNECTOR:
		MODEM:
		SIM TRAY:
		3.3V LDO:
		1.8V LDO:
		3V LDO:	

Revisions