Module Enable; Pwm - Sierra Wireless AirPrime BX3100 Hardware Integration Manual

Hardware Integration Guide
Rev 3 Sep.18
SDIO is particularly susceptible to tracking impedance and length variations between
the SDIO tracks. Ensure that controlled impedance tracking is used, and minimize
tracking length between the module and SD slave device. Add series resistor
footprints at the host end to decrease the drive current and reduce potential
interference, and match the length of all the SD tracks to within 1 mm.
SDIO tracking can cause significant radiated interference at integer multiples of the
SD clock frequency, which can be picked up by the BX310x antenna. Bury SDIO
tracks between ground planes and ensure stitching ground vias are placed throughout
the board surrounding the SDIO tracking.
SDIO timing during the boot process is provided by GPIO(5) and GPIO(15). See
Table 4-9 on page 20 for details.

4.10 Module Enable

The AirPrime BX310x uses the ENABLE (Module Enable) signal to turn the module
on/off:
• Turn module on—Drive ENABLE high (to VDD_PADS_BB)
• Turn module off—Drive ENABLE low (to 0V)
Table 4-12: Enable Pin Description
Pin Signal Name Direction
b
37 ENABLE
a. Signal direction with respect to the module.
b. Do not leave this pin unconnected.
To avoid a possible implementation-dependent issue where enabling/disabling Wi-Fi
functionality could cause a perturbation (glitch) on the power supply rails that impacts
module operations, a short delay (1 ms recommended) is required for the power
supply to stabilize before enabling the module.
If ENABLE is controlled by the Host, the host implements the delay (from the time the
supply is present) before driving ENABLE high.
If ENABLE is hard-wired to the supply (VDD_PADS_BB), an RC circuit (10k &
0.1uF) is required. The RC circuit will create the required delay, allowing the supply to
stabilize before ENABLE is pulled high.
Do not leave this pin unconnected.

4.11 PWM

The AirPrime BX310x supports the use of PWM functionality on GPIOs (GPIO(5) and
GPIO(27)) via AT command configuration. Refer to [1] AirPrime BX310x AT Command
Reference for details.
a
Function
I Start/stop module VDD_PADS_BB
22
Voltage Level
41112607