1. Register access problem in Belle2Link
M. Shoji (KEK)
and
S. Nishida (KEK)

2. ARICH Electronics
(FE)
Merger
FE ASIC
FE FPGA
Belle2Link (B2L)

3. Use of slow control in ARICH
We use B2L slow control for
Parameter setting of the FE
Data volume : ~ 16 Kbit
Download of FE FPGA firmware
Data volume : ~ 3 Mbyte

4. Problem observed in the slow control in the ARICH
Failure in reading the register value.
The problem occurs randomly; it occurs even when the data readout is not done.
Once the problem happens, the read out value becomes always the same.
The recovery can be done only by re- downloading the HSLB firmware.
(Here, I call “hang-up” problem)

5. Read/Write test of the slow control normal condition
Logic analyzer(FEE monitor)
(Read/Write the lower 8bit)
write
write value = 0x05
read
read value = 0x05
PC monitor
write value = 0x05
read value = 0x05
Read value is consistent.

6. Read/Write test of the slow control when the problem happens
Logic analyzer(FEE monitor)
(Read/Write the lower 8bit)
write
write value = 0x05
read
read value = 0x05
PC monitor
write value = 0x05
read value = 0x01
Read value is inconsistent.

7. Check the HSLB status with “staths” command
Normal condition
During the problem
Error
Once the problem happens, the returned value from HSLB is always the same
For recovery, HSLB firmware needs to be downloaded again.

8. COPPER Driver
The hang-up problem might be dependent to the COPPER driver (?)
/dev/copper/fngeneric : more frequently happened.
/dev/copper/hslb : ARICH is now using this driver.

10. Other problem : access too slow
We send FE FPGA firmware using the slow control.
Data volume : ~ 3 Mbyte
We add 10 usec of usleep() at each access (to avoid the hang-up problem).
Runtime : 5h30m
Too slow !!
With SiTCP operation, it takes only 1 min or so.
If “Batch mode” helps, we want to try (but DAQ people don’t know about it).

11. Hand-shake access
Another possible solution may be to check the status of HSLB after sending slow control data: ( i.e. write operation  check HSLB status  send next bit if OK, otherwise usleep() for a while).
Concern: the register access to check the HSLB status may cause the slow control hang- up problem.
Not tried yet, but this method work only if we can drastically reduce usleep() in the program.