am79c30a Advanced Micro Devices, am79c30a Datasheet - Page 11

• Manufacturer Part Number: am79c30a
• Description: Digital Subscriber Controller ?dsc ?circuit
• Manufacturer: Advanced Micro Devices

Bc buffers must be accessed within 122.4 µs. This is to
prevent erroneous data transfers. Only one interrupt is
used to signal accessibility for both B channels of the S
Interface. Since the data transfer must occur synchro-
nously to the S Interface, any data access to either Bb
or Bc or both must be made within the122.4 µs limit.
Note that even though only a single interrupt is issued,
either or both S-Interface B channels must be serviced.
IR bits 2, 3, 5, 6, and 7, if set, indicate that a bit has
been set in the associated status or error register. All of
the interrupts generated by the Am79C30A/32A can be
Am79C30A/32A Data Sheet
individually disabled. In the case of IR bit 7, the inter-
rupt can also be masked by setting PPIER bit 7 to 0.
DMR1, DMR2, DMR3, LMR2, MCR4, and MF control
the mask conditions that affect the INT pin. The INT pin
is activated only by interrupts that are not disabled. The
Interrupt Register reflects the status of enabled inter-
rupts. The INT pin can be disabled by setting INIT Reg-
ister bit 2 to a logical 1.
The Am79C30A/32A has facilities that allow the micro-
processor to read the status registers (status update is
inhibited during status read) or the IR at any time dur-
ing functional operation.
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