User Manual

AMPLIFIER CONTROLLER BOARD REV.5
PUB12-030 Rev. 1 Feb 14, 2013 12-030-19 Amplifier Controller Board Rev.5
5 CIRCUIT DESCRIPTIONS
5.1 MC68HC9S08 MICROPROCESSOR
The Motorola MC68HC9S08GT microprocessor (often referred to as the CPU or HCS08) performs all of the
control interface and communications in the MXi transmitter system. It is a 44-pin surface mount PLCC type
device that is permanently soldered to the circuit board and is not field serviceable or easily replaced without
special surface mount tooling. A brief description of the part is given in this section and a portion of the
manufacturer’s documentation is given in Appendix A. More detailed information on this part can be obtained from
the Motorola web site.
The HCS08 chip used in the MXi can come with up to 128 Kbytes of non-volatile flash memory, which can be
erased and reprogrammed to allow updating of software code or system parameters. The MXi code is typically
smaller than 8k and so would fit into all models of Flash memory. The HCS08 chip has a dedicated serial input pin
designated as the BDM (Background Debug Mode) port that is used to program the internal Flash memory and
for debug testing. The MXi is programmed at the factory and it is not expected that reprogramming would need be
done in the field, although it is possible to do with the proper software. System parameters and status that need to
be retained during power failures (such as the LOG entries) are also stored in the Flash memory.
Most of the external pins on the HCS08 are configured as programmable Input/Output (I/O) ports, where the
software program determines whether a certain pin is to be configured as either an input or output. The pins on
the HCS08 are grouped together in sets called PORTs. These Ports will have eight pins (or fewer) to support the
byte wide data path in the CPU. Port A is used for general system inputs and outputs. Port B is used as an eight-
channel A/D converter to measure system telemetry values. Port C is used for general system inputs and outputs.
Port D assigns four pins for the synchronous serial port (SPI) with the other four pins used for system inputs. Port
E assigns two pins as a serial communications port (SCI), one pin is the external CPU clock and the other two
pins used for general system inputs and outputs.
The definition of each Port pin is as follows:
PORT A
PA0 Input or Output Jumper E3 configures as I/P or O/P
PA1 Input VSWR Trip Status
PORT B
PB0 Telemetry Temperature of Heatsink [Optional]
PB1 Telemetry Power Supply Current
PB2 Telemetry Power Supply Volts
PB3 Telemetry Cutback Volts [Scaled at half the actual value]
PORT C
PC0 Input 50V Power Supply OK Status
PC1 Input Thermal Interlock
PC2 Output Digi Ethernet Reset Control
PC3 SCI2 Transmit Data Used by Remote Controls
PC4 Output Remote Status – Error
PC5 SCI2 Receive Data Used by Remote Controls