bt8970 Mindspeed Technologies, bt8970 Datasheet - Page 12

• Manufacturer Part Number: bt8970
• Description: Single-chip Hdsl Transceiver
• Manufacturer: Mindspeed Technologies

1.0 System Overview
1.1 Functional Summary
1.1.4 Microcomputer Interface
The Microcomputer Interface (MCI) provides access to a 256-byte address space within the transceiver. A
combination of direct and indirect addressing methods are used to access all internal locations. The MCI is
designed to interface with both Intel- and Motorola-style processors with no additional glue logic. A MOTEL
control pin is provided to configure the bus interface control/handshake lines to conform to common
Motorola/Intel conventions. A MUXED control pin is provided to configure the bus interface address and data
lines for multiplexed or independent data/address bus operation. Little-endian data formatting (least significant
byte of a multibyte word stored at the lowest byte-address location) is used in all cases, regardless of MOTEL
pin selection. A READY control pin is provided to support wait-state insertion. An Interrupt Request (IRQ)
output pin supports low-latency responses to time-critical events within the transceiver.
various metering functions within the receiver section and off-load the external microcomputer from complex
timing operations associated with startup procedures. Control and monitoring access to the timers and meters is
provided through the microcomputer interface.
1.1.5 Test and Diagnostic Interface (JTAG)
The Test and Diagnostic Interface comprises a test access port and a Serial Monitor Output (SMON). The test
access port conforms to IEEE Std 1149.1-1990, (IEEE Standard Test Access Port and Boundary Scan
Architecture). Also referred to as Joint Test Action Group (JTAG), this interface provides direct serial access to
each of the transceiver’s I/O pins. This capability can be used during an in-circuit board test to increase the
testability and reduce the cost of the in-circuit test process.
signals. The programmable signal source is shifted out serially at 16 times the symbol rate. The majority of the
receive signal path is accessible through this output.
1-4
Eight 16-bit timers and ten measurement meters are integrated into the transceiver. The timers support
The serial monitor output can be viewed as a real-time virtual probe for looking at the transceiver’s internal
Preliminary Information/Conexant Proprietary and Confidential
Conexant
Single-Chip HDSL Transceiver
100101B
Bt8970