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A24 Interrupt Vector
Register
b+04
15
14
13
h
Write
Read
Command / Response
Register
b+20
15
14
13
h
Write
Read
66 Register Programming Information
The A24 Interrupt Vector Register is a read-only register at address 04
A24 memory. During an Interrupt Acknowledge Cycle or Read Interrupt
Vector Register Cycle, the value of this register is placed on the VXI data
bus and then cleared. The default value of this register is 0
12
11
10
9
8
Not used
•
After the host controller receives the Interrupt Vector Register value, it
should read the corresponding Interrupt Status Register to determine
the actual source/cause of the interrupt. For more information, refer to
the Interrupt Status/Control Register.
•
At power-on or reset, all bits are "0".
The Command / Response Register is a read/write register at address 20
A24 memory. This register is used to exchange commands and data between
the host controller and the microcontroller on the HP E2261A M-Module.
The default value (at power-on) of this register is 00
12
11
10
Not used
Not used
•
This register is used with the Parameter Registers (addresses 22
24
). The Parameter Registers must be set up before sending a
h
command value to the Command / Response Register. In the following
command descriptions, they are called PARM0 and PARM1.
•
The Command Status Register (address 26
signal for the Command / Response Register. Writing a value to the
Command / Response register clears the CPRDY bit (bit 0) in the
Command Status Register indicating that the Command / Parameter
registers are not ready for the next data. Usually, a "0" on CPRDY
interrupts the M-Module microcontroller. After the microcontroller
execute the command, it writes a response to the Response Register
and Parameter Registers. After sending the response, the
microcontroller sets CPRDY indicating it is ready for the next
command.
The following pages describe the HP E2261A microcontroller commands,
parameters, and results. In the description PARM0 represents Parameter 0
register (22
h
commands are listed in order of their hexadecimal command code.
The following command (hexadecimal) code includes two xx's followed by
the actual command code. The xx's (binary) represent the port number: 00 is
Port 1, 01 is Port 2, 10 is Port 3, and 11 is Port 4. For example, to set the Port
2 (01
) transmitter baud rate (xx21
binary
command: 01100001
7
6
5
4
Undefined
9
8
7
6
) and PARM1 represents Parameter 1 register (24
or 61
.
binary
h
.
h
3
2
ICH3
ICH2
ICH1
.
h
5
4
3
2
Command
Command Response
) acts as a handshake
h
h
or xx100001
), use the
h
binary
in
h
1
0
ICH0
in
h
1
0
and
h
). The
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