W66910 Datasheet, PDF (40/81 Pages) Winbond – TE Mode ISDN S/T-Controller with Microprocessor Interface

Data Sheet
W66910 PCI ISDN S/T-Controller
The microprocessor may either enforce a 1 (idle state) in MR, MX by setting the control bit MRC or MXC (MOCR register) to 0,
or enable the control of these bits internally by the W66910 according to the Monitor channel protocol. Thus, before a data
exchange can begin, the control bit MRC, or MXC should be set to 1 by the microprocessor.
The relevant status bits are:
• For the reception of Monitor data: MDR (Monitor Channel Data Received ) ⇔ MER (Monitor Channel End of Reception)
• For the transmission of Monitor data: MDA (Monitor Channel Data Acknowledged ) ⇔ MAB (Monitor Channel Data
Abort)
About the status bit MAC( Monitor Channel Transmit Active) indicates whether a transmission is progress.
• If set MAC = 0, the previous transmission has been terminated. Before starting a transmission, the microprocessor should
verify that the transmitter is inactive.
• If set MAC = 1, after having written data into the Monitor Transmit Channel (MOX) register, the microprocessor sets this
bit to 1. This enables the MX bit to go active (0), indicating the presence of valid Monitor data (contents of MOX) in the
corresponding frame.
The receiving device stores the Monitor byte in its MOR (Monitor Receive Register) and generates a MDR (Monitor Channel
Data Receive) interrupt status. Alerted by the MDR interrupt, the microprocessor reads the MOR register. When it is ready to
accept data, it sets the MR control bit MRC to 1 to enable the receiver to store succeeding Monitor channel bytes and
acknowledge them according to the Monitor channel protocol. In addition, it enables other Monitor channel interrupts by setting
Monitor Channel Interrupt Enable to 1.
The first Monitor channel byte is acknowledged by the receiving device setting the MR bit to 0. This causes a MDA (Monitor
Channel Data Acknowledge) interrupt status at the transmitter. A new Monitor channel data byte can now be written by the
microprocessor in MOX register. The MX bit is still in the active (0) state. The transmitter indicates a new byte in the Monitor
channel by returning the MX bit active after sending it once in the inactive state.The receiver stores the Monitor channel byte in
MOR register and generates a new MDR interrupt status. When the microprocessor has read the MOR register , the receiver
acknowledges the data by returning the MR bit active after sending it once in the inactive state.This in turn causes the transmitter
to generate a MDA interrupt status. This ″MDA interrupt ⇒ write data ⇒ MDR interrupt ⇒ read data ⇒ MDA interrupt ″
handshake procedure is repeated as long as the transmitter has data to send.
When the last byte has been acknowledged by the receiver (MDA interrupt status), the microprocessor sets the Monitor channel
Transmit Control bit MXC to 0. This enforces an inactive (1) state in the MX bit. Two frames of MX inactive signifies the end of
a message. Thus, a MER (Monitor channel End of Reception) interrupt status is generated by the receiver when the MX is
received in the inactive state in two consecutive frames. As a result, the microprocessor sets the MR control bit MRC to 0, which
in turn enforces an inactive state in the MR bit. This marks the end of the transmittion, making the MAC (Monitor channel
Active) bit return to 0.
During a transmission process, it is possible for the receiver to ask a transmission to be aborted by sending an inactive MR bit
value in two consecutive frames. This is effected by the microprocessor writing the MR control bit MRC to 0. An aborted
transmission is indicated by a MAB (Monitor Channel Data Abort) interrupt status at the transmitter.
7.9 8-bit Microprosessor Interface Circuit
At power up, the reset pin RST# must be asserted to initialize the chip. At rising edge of RST#, data value at CLK pin determines
the operation modes: HIGH for Intel bus mode, LOW for Motorola bus mode.
7.10 Peripheral Control
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Publication Release Date: Feb,2001
Revision 1.0