Hardware Overview - Silicon Laboratories Wireless M-Bus-EK User Manual

Wireless M-Bus-EK

3. Hardware Overview

The Wireless M-Bus Demo board has two sections. The Wireless M-Bus meter section is on the right half as
shown in Figure 2.
The Wireless M-Bus meter section includes the following components.
 C8051F930 Low-Power Microcontroller
®
 Si4431 EZRadioPRO
 CP2400 LCD Driver
The C8051F930 is well suited for Low-Power Metering solutions. This MCU includes 64 k of Flash and 4 k of RAM,
which is sufficient for the Wireless M-Bus stack and a large application. The C8051F930 has a very low-power
Sleep mode. The current consumption in Sleep mode is only 50 nA. The MCU also has a 32.768 kHz
TM
SmaRTClock . The MCU SmaRTClock
The Si4431 EZRadioPRO
868 MHz band used by the Wireless M-Bus Standard. The RF layout is matched for 868 MHz. The Si4431 is
placed in Shutdown mode when the radio is not in use. The current draw in shutdown mode is only 15 nA.
The CP2400 LCD driver features an SPI interface and can drive displays with up to 128 segments and four
backplanes. The Wireless M-Bus meter section uses a static four-digit display for the lowest possible power
consumption. The Meter Display is used to display either pulse count or Temperature. The Monitor Section is
shown in Figure 3.
2
Figure 2. Meter Section
Transceiver
TM
is used for all timing functions in the low-power meter.
®
transceiver provides +13 dB of output power. This is the highest power permitted in the
C8051F930
CP2400
Rev. 0.1
Si4431