Motorola ASTRO MT 1500, Руководство по обслуживанию, Страница: 93 / 817

6816985H01-B August 16, 2007
UHF1 Detailed Theories of Operation: VOCON Functional Blocks 4.2-9
4.2.6.1.3 Flash Memory (U803)
The Flash memory IC is a 8-megabyte CMOS device with simultaneous read/write or simultaneous
read/erase operation capabilities with 70 ns access speed. It is supplied with 1.8 volts. The Flash
memory has its 22 address lines and 16 data lines connected to the EIM of the Patriot IC through the
ADDR(23:0) and DATA(15:0) busses. The Flash memory contains host firmware, DSP firmware,
codeplug data, and tuning values.
The RESET_OUT of the Patriot IC (U800) is at the GPIO voltage logic level (see section 4.1.6.1.1.).
Components CR800 and R812 are used to convert the voltage down to a 1.8-volt logic level, and this
1.8 volt reset signal is fed to the Flash RESET pin. When this pin is asserted (active low logic), the
Flash is in reset mode. In this mode, the internal circuitry powers down and the outputs become high
impedance connections.
The Flash active low chip select pin, EN_CE, is connected to the active low CS0 pin (TP_CS0 test
point) of the EIM. When the EN_CE is not asserted, the Flash is in standby mode which reduces the
current consumption.
Several other active low controls pins determine what mode the Flash memory is in:
• the address valid pin ADV which is connected to the EIM LBA signal
• the output enable pin EN_OE that is connected to the EIM OE signal, and
• the write enable pin EN_WE which connected to the EIM EB1 signal.
For read mode, the ADV and EN_OE pins would be asserted while the EN_WE pin would not be
asserted. When the EN_WE is asserted and the EN_OE pin is non-asserted, the Flash would
operate in the write mode.
Figure 4.2-1. Controller Memory Interface
Patriot
U800
Flash
U803
SRAM
U804
RESET_OUT
LBA
CS0
EB1
OE
A(23:0)
D(15:0)
EB0
CS2
R_X*
3V to 1.8V RESET
ADV
EN_CE
EN_WE
EN_OE
A(22:0)
D(15:0)
A(18:0)
D(15:0)
EN_OE
EN_BLE
EN_BHE
EN_CE
EN_WE
CSO
A(23:1)
A(19:1)