CAEN V767 128 Channel Gen. Purpose MH TDC - Physics

02/07/2003 V767 User's Manual – Rev.4
4. OPERATING CODES
4.1. PROGRAMMING CAPABILITY
The module programming is performed by means of an on-board microcontroller. The
User sends and receives instructions and data to/from the microcontroller via 16-bit
OPCODE setup words. The handshake is the following:
Write Operation:
• the VME (master) tests the WRITE_OK bit in the Opcode Handshake Register (see
§ 3.21); if the WO bit is set to 1, the VME can write a datum;
• the WO bit is automatically reset after the datum is written and is set back to 1 when
the datum has been acquired by the server;
• when the WO bit is set back to 1, the VME can write another datum.
Read Operation;
• a valid datum can be read via VME only if the READ_OK (RO) bit in the Opcode
Handshake Register (see § 3.21) is set to 1;
• the RO bit is automatically reset after the datum is read out and is set back to 1
when a new datum is ready to be read out;
• when the RO bit is set back to 1, the VME can read another datum.
N.B.: because of V767 module's internal delays it is necessary to insert a 10-ms
delay in the software after the check of the RO/WO bit, i.e. before performing the
next R/W operation on the Opcode Register.
In general, three different types of operation can be performed:
1. write an opcode,
2. write an operand,
3. read an operand.
By default, at power-on or after a VME reset, the WO bit of the Handshake Register is
set to 1 and the RO to 0: actually, the first operation to be performed is always the write
operation of an opcode (operation of type 1).
Conversely, the operation of type 2 must be always preceded by the write operation of
an opcode which requires to write an operand: this is case, for example, of the opcode
‘SET_WIN_WIDTH’ which requires to input the operand ‘width of the window’. Similarly,
the operation of type 3 must be always preceded by a write operation of an opcode
which issues a read access: actually, this makes the RO bit of the Handshake Register
to be set to 1 in order to allow the following read operation. For example, the write
operation of the opcode ‘READ_WIN_WIDTH’ makes the RO bit of the Handshake
Register be set to 1 and in this way allows the following read operation.
NPO:
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