Tektronix Webcam 070-8030-01 Manual De Usuario
Theory of Operation
3–54
1780R-Series Service Manual
Diagram 19 UART & A/D
The Universal Asynchronous Receiver/Transmitter (UART) has both RS-232 and
RS-422 buffers for communication between the Master MPU (Diagram 16) and
external peripherals. By using two buffers and internal terminations it is possible
to use a single rear-panel 9-pin, D-type connector for both interface standards.
RS-422 buffers for communication between the Master MPU (Diagram 16) and
external peripherals. By using two buffers and internal terminations it is possible
to use a single rear-panel 9-pin, D-type connector for both interface standards.
The A/D Converter changes the 16 analog potentiometer signals into 8-bit digital
bytes for use by the Master MPU.
bytes for use by the Master MPU.
Also included on this diagram are the Remote Sync and RGB Input Amplifiers.
UART. U330 is a dual UART that runs at a clock frequency of 3.6864 MHz. It is
configured as an 8-bit peripheral activated whenever the Master MPU addresses
the UART address space. The chip select /UARTCS (from the Master MPU) is
the chip enable (CEN) for the UART. The /RD and /WR determine the type of
communication between the Master MPU and the connected external peripheral.
The clock signal is generated by U430, a CMOS oscillator.
configured as an 8-bit peripheral activated whenever the Master MPU addresses
the UART address space. The chip select /UARTCS (from the Master MPU) is
the chip enable (CEN) for the UART. The /RD and /WR determine the type of
communication between the Master MPU and the connected external peripheral.
The clock signal is generated by U430, a CMOS oscillator.
The remainder of the circuit consists of U495, an RS-232 buffer, and U395, an
RS-422 buffer. The receive outputs from these parts are NANDed (by U595C)
and input to the UART RXDA (Read External Data). This allows either an
RS-232 or RS-422 device to be connected to rear-panel J595, without having to
reconfigure the UART input. R393, R391, and R392 are a 120
RS-422 buffer. The receive outputs from these parts are NANDed (by U595C)
and input to the UART RXDA (Read External Data). This allows either an
RS-232 or RS-422 device to be connected to rear-panel J595, without having to
reconfigure the UART input. R393, R391, and R392 are a 120
W termination for
the RS-422 line which bias it to the inactive state when there is no connection to
Overview
Circuit Theory