Trip-T Front End Board Documentation Home
High Voltage Trimming
The HV trimDACs need to be set up before they can be used. This requires the following:
- Set SPI mux address.
- Write 0x8000 to register 64.
- Trigger load with trigger vector 0x80 and duration = 10.
- Write 0xA000 to register 64.
- Trigger load with trigger vector 0x80 and duration = 10.
- Write 0xc000 to register 64
- Trigger load with trigger vector 0x80 and duration = 10.
to be done for each TrimDAC on the board.
Values can then be loaded into the DAC registers. This requires the following:
- Set SPI mux address
- Write internal DAC address and DAC value into reg 64.
- Trigger load with trigger vector 0x80 and duration = 10
details of the DAC interface may be found in the datasheet.
There are 8 channels per DAC, thus each TripT requires 2 DACs. A
transparent mapping TripT IDs (0=A, 1=B, 2=C, 3=D) and channel numbers
(0-15 inclusive) can be achieved as follows (using c/c++ like notation):
- Reverse channel number: Channel No=15-Channel No.
- Generate SPI mux address = (TripTId<<1)|(ChannelNo/8)
- DAC Channel address = (Channel No)%8
- Format Value for Reg 64: (DAC Channel Addr<<12)|(DAC Code <<4)
N.B. This is for the 8bit dacs on the TFB v1/v2 boards.
The DACs do not permit read-back of the currently loaded values.
The HV has to be enabled for the board. This is achieved by writing a
1 into register 2.