How to mask DFBs in the ROMs
This is an attempt to explain how to mask a DFB from the configuration
process and from data taking.
You just need to edit the following file and then reboot the ROMs:
/nfs/bbr-srv02/dataflow/ir-2/drc/app/startup.DRC_COMMISSIONER
which looks like this:
# Sector 0
*dfbmasklist = 0xffff;
# Sector 1
*(dfbmasklist+ 4) = 0xffff;
# Sector 2
*(dfbmasklist+ 8) = 0xffff;
# Sector 3
*(dfbmasklist+12) = 0xffff;
# Sector 4
*(dfbmasklist+16) = 0xffff;
# Sector 5
*(dfbmasklist+20) = 0xffff;
# Sector 6
*(dfbmasklist+24) = 0xffff;
# Sector 7
*(dfbmasklist+28) = 0xffff;
# Sector 8
*(dfbmasklist+32) = 0xffff;
# Sector 9
*(dfbmasklist+36) = 0xffff;
# Sector 10
*(dfbmasklist+40) = 0xffff;
# Sector 11
*(dfbmasklist+44) = 0xffff;
In order to mask a DFB you just need to replace the ffff string in the corresponding sector.
DFB numbering in the ROMs
In the DIRC language, the DFBs go from 0 to 13, where DFB #13 is the
closest to the DCC. In the following picture we see the 14 DFBs, where the DFB #0 is the first one on the left;
the DCC is located after the last DFB on the right, outside the picture.
In the ROMs, the DFBs are
numbered in the opposite direction, where 0 corresponds to the DFB closest to the DCC.
So the DIRC and DataFlow schemes are:
| DIRC |
|
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
DCC |
| Dataflow |
|
13 |
12 |
11 |
10 |
9 |
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
DCC |
Instead of going into explanations of hex and binary languages,
let us just explain a method to count and figure out which
bit we have to change to mask a DFB.
This is the configuration when all DFBs are active
| Hex |
|
|
f |
|
|
|
|
f |
|
|
|
|
f |
|
|
|
|
f |
|
| Bin |
1 |
1 |
1 |
1 |
|
1 |
1 |
1 |
1 |
|
1 |
1 |
1 |
1 |
|
1 |
1 |
1 |
1 |
| DFB (DataFlow) |
13 |
12 |
11 |
10 |
|
9 |
8 |
7 |
6 |
|
5 |
4 |
3 |
2 |
|
1 |
0 |
When we want to mask a DFB, we need to set to 0 the corresponding bit in the binary
representation and then translate it in hexadecimal represantation, for instance:
if we want to mask DFB #10 (in DIRC convention) in sector 5, we apply the following procedure:
- Translate the DFB number in DataFlow scheme:
by looking at the first table, DFB #10 becomes DFB #4;
- change the corresponding 1 into a 0 in the binary representation;
| Bin |
1 |
1 |
1 |
1 |
|
1 |
1 |
1 |
1 |
|
1 |
0 |
1 |
1 |
|
1 |
1 |
1 |
1 |
| DFB (DataFlow) |
13 |
12 |
11 |
10 |
|
9 |
8 |
7 |
6 |
|
5 |
4 |
3 |
2 |
|
1 |
0 |
|
|
which becomes 1011;
- Use the following table to convert the binary number in hexadecimal
|
|
|
| Hex |
Bin |
Dec |
| 0 |
0000 |
0 |
| 1 |
0001 |
1 |
| 2 |
0010 |
2 |
| 3 |
0011 |
3 |
| 4 |
0100 |
4 |
| 5 |
0101 |
5 |
| 6 |
0110 |
6 |
| 7 |
0111 |
7 |
| 8 |
1000 |
8 |
| 9 |
1001 |
9 |
| a |
1010 |
10 |
| b |
1011 |
11 |
| c |
1100 |
12 |
| d |
1101 |
13 |
| e |
1110 |
14 |
| f |
1111 |
15 |
we see that the bit 1011 becomes b
in hexadecimal language1 ;
- We now need to save the current DFB masking file:
/nfs/bbr-srv02/dataflow/ir-2/drc/app > cp startup.DRC_COMMISSIONER startup.DRC_COMMISSIONER_YYYYMMDD
- at this point we can change the corresponding line in startup.DRC_COMMISSIONER:
# Sector 5
*(dfbmasklist+20) = 0xffbf;
- Watch out, the actual masking file is called
startup, which should become the link to your new file
/nfs/bbr-srv02/dataflow/ir-2/drc/app > ls -l startup
lrwxrwxrwx 1 babardrc bfactory 21 Mar 2 17:58 startup -> startup.DRC_COMMISSIONER
- at this point you just need to reboot the ROMs.
1Yes, this is the guide for stupid people
Emmanuele Salvati
Last modified: Fri Apr 20 15:19:39 PDT 2007