WIENER, Plein & Baus GmbH
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5 GUIDE TO LIST MODE DATA ACQUISITION WITH CC-USB
CC-USB is intended for use in list mode data acquisition, where it performs sequences of
desired CAMAC operations pursuant to stack(s) stored in it, upon receipt of event trigger.
CC-USB then formats the data read form the CAMAC bus and buffers them in a data buffer.
When the buffer is full, CC-USB transfers its content to the In FIFO of the USB controller IC
for a readout by host software.
To set up CC-USB for data acquisition in list mode one nedds to do the following:
1. Build the regular stack by adding all the desired simple and complex commands to it.
One must make sure that the stack sequence will clear all CAMAC modules. It is
recommended to first execute the stack from the host software to verify that it
performes as intended. One may use here the libxxusb library function
xxusb_stack_execute.
2. Load the stack into the CC-USB memory, e.g., by calling the libxxusb library
function xxusb_stack_write. It is recommended to read back the stack (function
xxusb_stack_read), to verify that the stack is correctly stored.
3. When the setup calls for it, build and load the scaler stack.
4. Set up the data acquisition trigger mode. By default, CC-USB commences execution
of the stack upon receipt of a NIM signal at its user NIM input I1.
5. Set the trigger delay (time from the receipt of an event to the commencement of the
stack execution) and LAM timeout.
6. Set up event termination mode. By default, CC-USB terminates every event by one
terminator word 0xFFFF.
7. Set up buffering mode and data buffer length by writing a suitable 4-bit code into bits
0-3 of the Global Mode Register. The default is buffer length of 4096 words and
events fitting into one buffer.
8. Set up CAMAC bus arbitration, if necessary. The default is no arbitration.
9. Set buffer header option. By default, CC-USB writes one buffer header word
containig information on the number of events in the buffer, buffer type (regular, or
periodic scaler), and the buffer termination mode (regular or watchdog).
10. Start acquisition by setting bit 0 of the Action Register to 1. End acquisition by
resetting this bit to “0”. While in acquisition mode, the host software is expected to
read the USB port In FIFO in a loop, to empty it and make space for subsequent
events.
