Справочник Пользователя для IP Mobilenet LLC M32450-25

 

 

M32450-25-FCCRpt.doc  

Page 5

 

 
M32450-25 Mobile Radio Section Descriptions 

 

 

 

The M32450-25 Mobile Radio works within a frequency range of 450 to 512 MHz and requires a 1/4-
wavelength antenna. 

 

 
This section provides detailed descriptions of each of the sections within the M32450-25 Mobile Radio.  
Refer to Appendix A to view the M32450-25 Mobile Radio Circuit Board Diagram. 
 
 
 
Microcontroller

 
The microcontroller (U30) is a major component of the radio as it manages the operation of the radio.  It 
also controls the operation of the modem, and determines which receiver provides a better signal from a 
given transmission.  It provides transmit time-out protection in the event a fault causes the radio to halt in 
the transmit mode.  It utilizes a reduced instruction set computer (RISC) architecture which provides low 
power operation and a powerful instruction set.  Other features include a watchdog timer, serial universal 
asynchronous receiver/transmitter (UART), two 8-bit timers, and 2 KB of electrically erasable 
programmable read only memory (EEPROM) storage. 
 
NOTE: 

The EEPROM Random Access Memory (RAM) stores the setup data entered by the 
technician even if there is a loss of power. 

 
 

Support circuitry 
 
The support circuitry consists of the following:   

 

ƒ

  A Supervisor Control Chip (U25) provides power-on reset. 

 

ƒ

  The clock controls microcontroller operation and is generated by crystal Y3 and a Pierce oscillator 

circuit (inside the U30-microcontroller). 

 

ƒ

  The latch (U28) decodes low order address bits (A0-A7) from the address/data bits (AD0-AD7).  It is 

controlled by Address Latch Enable (ALE) output of U30 and the bits are used by the modem. 

 

ƒ

  A 512Kx8 Static RAM Chip (U31) provides temporary storage of the radio’s configuration data 

facilitating the technician with access to make changes. 

 

ƒ

  Control logic is also an important part in the microcontroller section.  The RAM chip select (RAMCS*) 

and modem chip select (MODEMCS*) command lines are created by U26A, U27BCD, and U44ABC.  
These gates decode four (4) high order address bits (A11-A15).  The RAM is addressed by five (5) 
memory addresses (MA14-MA18) bits decoded by U26D, U27A, and U24.  This logic decodes port 
address bits (PA14-PA18) to produce memory address bits (MA14-MA18) for the RAM chip. 

 
 
Input/Output 
 
Input/output components convert serial and handshake data from the modem section to RS232 levels, 
and vice-versa.  Chip U22 is an RS232 transmitter and receiver.  It converts data in 5-volt logic form to 
data in +/-12-volt form, as required by the RS232 standard.  A charge pump power supply on the chip 
converts the +5-volt DC logic power on pin 26 to the +12-volt and –12-volt levels required.  Capacitors 
C106-C109 generate these voltages by a charge pump.  These values determine the operating voltages.