6.
Servicing
Hardware technical description
This section gives an overview of the hardware used in the RM-4. Detailed specifications can be
found in the Appendices.
Microprocessor
The microprocessor used on the RM-4 is a Motorola PowerPC Quad Integrated Communications
Controller (QUICC). The central processing unit (CPU) uses 32-bit PowerPC architecture
incorporating 4 Kbyte data and instruction caches. The processor operates at a system clock speed
of up to 25 MHz and is equipped with several power-saving modes.
The capabilities of the QUICC include a communications processor module (CPM) with four serial
communications controllers (SCC) and two serial management controllers (SMC). The CPM
supports communications using Ethernet protocol.
The microprocessor has a serial peripheral interface (SPI) which is used to communicate with the
state-of-health (SOH) analog-to-digital converter (ADC).
The processor can interface with up to 4 Mbytes of SRAM for temporary storage and 4 Mbytes of
flash memory for code storage and execution.
Ethernet Communications
One of the SCCs on the PowerPC is dedicated to Ethernet communications, via a Motorola
MC68160 Ethernet controller.
Serial Communications
A quad universal asynchronous receiver transmitter (UART) is used to provide four additional
serial communications channels. These channels, along with three SCCs and one SMC of the
PowerPC, comprise the eight external serial ports on the RM-4. All of these ports are equipped with
RS-232 transceivers, and EMI suppression using ferrite beads. Surge protection is provided on all
external serial connections using bi-directional transorbs which clamp external voltages at ±7.5 V.
The remaining SMC on the PowerPC is used to communicate with the GPS engine.
State-of-Health
State-of-health (SOH) measurements are provided using a 10-bit 8:1 multiplexing ADC. Temperature
is sensed using an on-board sensor, as is battery voltage and external SOH measurements. Surge
protection is provided on all external SOH connections using bi-directional transorbs which clamp
external voltages at ±36 V. EMI suppression is provided with ferrite beads.
Basic troubleshooting
Status LED does not come on
Disconnect the power supply and check that +5V is on pin 3 of the power supply connector (for a
standard RM-4), or that +12V is on pin 5 (for an RM-4 configured to operate on 12V).
Check the on-board fuse as described in the section below, “Maintenance: Checking and replacing
the on-board fuse” .
6 - Servicing
RM-4 Manual 31
Summary of Contents for RM-4
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