Motorola ASTRO MT 1500, Service Manual

Page: 146 / 817

August 16, 2007 6816985H01-B
4.5-6 900 MHz Detailed Theories of Operation: VOCON Functional Blocks
4.5.6.1.1.1 Microcontroller Unit (MCU)
The MCU portion of the Patriot has 22.5Kx32 bits of internal RAM and 1Kx32 bits of internal ROM.
The internal ROM is used for the bootstrapping code. The MCU has several peripherals, including
the following:
• an External Interface Module (EIM)
• the Multiple Queue Serial Peripheral Interface (MQSPI)
• two Universal Asynchronous Receiver/Transmitter (UART) modules, and
• the One-Wire Interface module.
The MCU communicates internally to the DSP through the MCU/DSP Interface (MDI).
External Interface Module (EIM)
The External Interface Module (EIM) is the MCU's interface to the SRAM (U804), Flash Memory
(U803), and the display. The EIM lines include the following:
• 24 external address lines
• 16 external bi-directional data lines
• 6 chip selects lines
• read/write line, and
• output enable line, among others.
All of the EIM lines operate at 1.8-volt logic levels; the EIM operates at the MCU clock speed.
Multiple Queue Serial Peripheral Interface (MQSPI)
The Multiple Queue Serial Peripheral Interface (MQSPI) is the MCU's programming interface to
other ICs. The Patriot has two independent SPI busses, and each has its own clock line, data-out
line (MOSI), and data-in line (MISO). There are 10 SPI chip selects (SPICS) that are programmable
to either SPI A, the RF board's SPI bus, or to SPI B, the dedicated VOCON SPI bus. The devices on
the SPI A bus include the following:
• the PCIC and FRACN IC on the SPICS4, and
• the ABACUS III on SPICS5.
There is one SPI B chip select used for the MAKO IC U701 on SPICS2 (TP_MAKO_CE). All of the
lines of the SPI module operate at the GPIO voltage logic level (see section 4.5.6.1.1.).
There are several devices on the RF board that only have one bi-directional SPI data line.
Components U801, U802, and Q801 are configured by the MCU GPIO pin TOUT13 (MISOA_SEL)
to route the data line to the appropriate pin on the Patriot depending on which SPI device is being
accessed.
Universal Asynchronous Receiver/Transmitter (UART)
The Patriot has two Universal Asynchronous Receiver/Transmitter (UART) modules. UART1
(primary UART) handles the RS 232 lines while UART 2 is not used. The primary UART has the
following lines:
• a receive data line URXD
• a transmit data line UTXD, and
• hardware flow control signals RTS (request to send) and CTS (clear to send).
All UART lines are operating at the GPIO voltage logic level (see section 4.5.6.1.1.).