Product Info

DRAFT 8-1-2019 Technical Brief
A c l a r a R a d i o M o d u l e I m p l e m e n t a t i o n R e q u i r e m e n t s 5
ARM Test Board for Certification
The following image shows the Aclara Radio module mounted on a test board
used for certification qualification.
The ARM Circuitry of the Test Board
There is a microcontroller that interfaces with the ARM using a Serial Peripheral
Interface (SPI). The SPI interface is where all data communications occur
between the Host microcontroller and the RF transceiver of the ARM. Both
commands and data are passed over the SPI interface. Digital signal levels for the
SPI interface are 3.6 V. The SPI interface uses buffered CMOS inputs and
outputs. There is a 64-byte TX/RX FIFO buffer internal to the Si4467. The SPI
interface only allows data transfer to the transceiver and has no effect on the
modulation or data rate of the RF transmitted signal.
A non-contact communication coil is used to control the test board and put the
radio into any desired operating mode. Aclara provides a communication puck
that when placed next to the communication coil, forms a loosely coupled
transformer. On-Off-Keying is then used at a baud rate of 1200 to pass bi-
directional data between a controlling device (PC or handheld device) driving the
puck (via USB port) and the test board. This is only one method of
communicating with the ARM’s host microcontroller. Other methods such as
direct connect serial ports or opto-isolated serial interfaces can also be used to
control the host microcontroller in an end point device. Communications with the
host microcontroller is only required during production testing and device
installation. The interface for external host microcontroller communications will
not affect the signaling of the SPI interface for the ARM.
The power supply provides a regulated 3.6 VDC output to power the ARM module.
Nominal test board input voltage is 3.6 V, but it can be varied between 3.0 V and
4.2 V. The on-board power supply is a buck-boost topology and will keep