User's Manual

Flairmesh Technologies Confidential -15-
3 Physical Interfaces
3.1 Power Supply
There are two power supply schemes available for the module. It can be powered by a Li-poly battery
(3.7V) or a 3.3V DC. Please refer to the reference designs in 5.
3.2 Reset
The module may be reset from several sources: RESETB pin, power-on reset, USB charger attach reset
and software configured watchdog timer.
The RSTB pin is an active low reset. It is recommended that RSTB be applied for a period greater than
120us.
At reset the digital I/O pins are set to inputs for bi-directional pins and outputs are tri-state. The pull-down
state is shown below.
Pin Name / Group
Pin Status on Reset
USB_DP
Tristate
USB_DN
Tristate
PIO0
No Pull
PIO[1,3,11,14]
PUS
PIO[4,5,16,60]
PDW
Table 15: Pin Status on Reset
Note: PUS – Strong pull-up, PDS – Strong pull-down, PUW – Weak pull-up, PDW – Weak pull-down.
If RSTB is held low for > 1.8 s and VCHG is not applied, the module turns off. A rising edge on PIO0 or
VCHG is then required to power on.
3.3 Audio Interfaces
3.3.1 Digital Audio Interface
Audio digital interfaces include:
! Digital microphone inputs
! Standard I"S/PCM interface (Input only)
3.4 General Purpose Analog IO
The module has three general-purpose analogue interface pins multiplexed with LED pads. In a Li-poly