CD2481 Datasheet, PDF (112/222 Pages) Intel Corporation – Programmable Four-Channel Communications Controller

CD2481 — Programmable Four-Channel Communications Controller
9.0
Detailed Register Descriptions
9.1
Global Registers
9.1.1
Global Firmware Revision Code Register (GFRCR)
Register Name: GFRCR
Register Description: Global Firmware Revision Code Register
Default Value: x’0D
Access: Byte Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Intel Hex Address: x’82
Motorola Hex Address: x’81
Bit 2
Bit 1
Bit 0
Firmware Revision Code
9.1.2
This register serves two functions in providing the host with information about the CD2481. When
the CD2481 is initialized by a hardware RESET signal, or by a software ‘Reset All’ command
issued through any Channel Command register, the CD2481 zeros this register at the start of the
initialization. At the conclusion of the initialization, the CD2481 writes firmware revision code to
the GFRCR. All valid CD2481 revision codes are non-zero, the revision code is incremented by
one with each new release, for example, GFRCR for Revision A = DD hex, Revision B is DE hex,
Revision D is E0 hex.
Host software must confirm that the GFRCR contents are non-zero before proceeding to configure
the CD2481 for normal operation.
Channel Access Register (CAR)
Register Name: CAR
Register Description: Channel Access Register
Default Value: x’03
Access: Byte Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
Reserved
Bit 3
Intel Hex Address: x’EC
Motorola Hex Address: x’EE
Bit 2
Bit 1
C1
Bit 0
C0
This register contains the channel number for the channel-oriented host read or write operations,
when the host is not in an interrupt service routine. The CD2481 supplies the interrupting channel
number during all interrupt service operations. The Channel Access register contents are not used
during an interrupt service. Note that this means that an interrupt service routine is restricted to
accessing only the register set of the Interrupting Channel and Global registers.
Bits 7:2
Reserved – must be zero.
Bits 1:0
Channel number
112
Datasheet