PC87393VJG National Semiconductor, PC87393VJG Datasheet - Page 97

• Manufacturer Part Number: PC87393VJG
• Description: IC, SUPER I/O DEVICE, TQFP-100
• Manufacturer: National Semiconductor

Specifications of PC87393VJG

• Data Rate: 2Mbps
• Supply Voltage Range: 3V to 3.6V
• Logic Case Style: TQFP
• No. Of Pins: 100
• Operating Temperature Range: 0°C to +70°C
• Termination Type: SMD
• Transceiver Type: Interface
• Rohs Compliant: No

6.0 Musical Instrument Digital Interface (MIDI) Port
6.2.1
The Internal Bus Interface Unit handles all read and write transactions between the host and the registers of the MIDI Port.
It also controls the MIDI Port interrupt request logic (see Section 6.2.8).
6.2.2
A Control register (MCNTL, see Section 6.3.6) and a Status register (MSTAT, see Section 6.3.4) allow the user to control
the operation of the MIDI, and provide status information regarding its various functional units. A Command register (MCOM,
see Section 6.3.5) allows the user to control the operation mode of the MIDI Port by serving as a port via which the host can
issue commands to the MIDI. A MIDI Port command is defined as a write access to the MIDI Command register. The mean-
ing of each command is determined by the data byte written during this write access.
6.2.3
The Data Buffers and FIFOs function as a mechanism for synchronizing between the Internal Bus Interface Unit and the
MIDI Communication Engine. This synchronization allows each of these units to handle its own tasks without having to
pause to send/receive data to/from the other unit. Synchronization also bridges the gap in the data transfer rate between
these two units. Data transfer rate matching is done when the FIFOs of the MIDI Port are enabled. It allows the MIDI Port to
interface a bus at a relatively high data transfer rate, while maintaining communication with a MIDI device over a communi-
cation channel that supports a relatively low data transfer rate.
6.2.4
The MIDI Communication Engine handles the serializing of outgoing data and the de-serializing of incoming data transferred
between the MIDI Port and the MIDI device. During transmit (serial data transfer from the MIDI Port to the MIDI device), the
Communication Engine receives data bytes from the output data buffer or FIFO, serializes them into a stream of data bits,
and transmits them as a sequence of high and low pulses over the MDTX pin according to the MIDI communication protocol.
During receive (serial data transfer from the MIDI device to the MIDI Port), the Communication Engine receives a sequence
of high and low pulses via the MDRX pin, converts them into a stream of data bits and de-serializes them into data bytes
that it sends to the input data buffer or FIFO.
Both transmit and receive are performed at a fixed serial data rate of 31.25 Kbits per second. The serial data format is also
fixed, and consists of 1 Start bit, 8 Data bits and 1 Stop bit. See the waveform illustrating a MIDI byte transfer in Figure 19.
Internal Bus Interface Unit
Port Control and Status Registers
Data Buffers and FIFOs
MIDI Communication Engine
SuperI/O
Internal
Bus
Read/Write
Interface
Interface
Internal
Unit
Bus
Status and Control
Asynchronous
Interface
Tx Data
Rx Data
Control
8
8
Data Buffer
Figure 18. MIDI Port Block Diagram
Buffers
FIFOs
Data
and
Control and Status
Synchronous
Interface
Tx Data
Rx Data
Control
MIDI Port
Registers
8
8
97
(Data Serializer)
Communication
Engine
MIDI
Communication
Status and Control
(Continued)
Transmit
Receive
Signal
Signal
MIDI
MIDI
Routing
Signals
Control
MIDI
Routing
Control
MDTX Pin
MDRX Pin
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