Adc/Voltage Measurement - Sierra Wireless AirPrime BX3100 Hardware Integration Manual

Hardware Integration Guide
Rev 3 Sep.18
· Common baud rates are supported—any baud rate in the supported range
can be selected via AT+IPR=<uart_baud_rate> command. The device
automatically configures the clock dividers appropriately for the chosen baud
rate.
· Baud rates are persistent post-reset.
· Recommendation—Add series termination resistors close to the module in
the UART lines for management of clock harmonics. 499 resistors are
recommended.

4.3 ADC/Voltage Measurement

The AirPrime BX310x provides a general purpose ADC (Analog to Digital Converter)
input, which can sample multiple inputs configured using AT commands.
Pins VDET_1, VDET_2, SENSOR_VP, and SENSOR_VN are used to measure
single-ended analog voltages referenced to ground. The voltage on these pins is read
via an AT command.
Noise can have a large impact on sensitive voltage measurements. To improve the
accuracy of small voltage level measurements, a100 nF capacitor to ground is
recommended on the input to the VDET_1, VDET_2, SENSOR_VP, and
SENSOR_VN pins.
Table 4-2: ADC Interface Pins
Pin Signal name
18 VDET_1
19 VDET_2
a. Leave open any pins that are not used.
b. Signal direction with respect to the module.
Table 4-3: Voltage-measurement GPIO Pins
Pin Signal Name
31 SENSOR_VP
32 SENSOR_CAPP
34 SENSOR_CAPN
36 SENSOR_VN
a. Leave open any pins that are not used.
b. Signal direction with respect to the module.
Access to a Hall effect sensor is supported via firmware, and is selected using AT
commands.
The sensor pins (SENSOR_VP or SENSOR_VN) will trigger an input perturbation
(glitch) lasting for 80 ns when the ADC or Hall sensor is initialized.
a
b
Direction
Function
I
Analog to Digital Converter
I
b
Direction Voltage level
I
I
VDD_PADS_BB
I
I
16
Voltage Level
VDD_PADS_BB
a
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