# timetag_core_regs

### Time-tagging core registers

Wishbone slave for registers related to time-tagging core

### Contents:

1. Memory map summary
2. HDL symbol
3. Register description
3.1. Timetag seconds register (upper)
3.2. Timetag seconds register (lower)
3.3. Timetag coarse time register, system clock ticks (125MHz)
3.4. Time trigger seconds register (upper)
3.5. Time trigger seconds register (lower)
3.6. Time trigger coarse time register, system clock ticks (125MHz)
3.7. Trigger time-tag seconds register (upper)
3.8. Trigger time-tag seconds register (lower)
3.9. Trigger time-tag coarse time (system clock ticks 125MHz) register
3.10. Acquisition start time-tag seconds register (upper)
3.11. Acquisition start time-tag seconds register (lower)
3.12. Acquisition start time-tag coarse time (system clock ticks 125MHz) register
3.13. Acquisition stop time-tag seconds register (upper)
3.14. Acquisition stop time-tag seconds register (lower)
3.15. Acquisition stop time-tag coarse time (system clock ticks 125MHz) register
3.16. Acquisition end time-tag seconds register (upper)
3.17. Acquisition end time-tag seconds register (lower)
3.18. Acquisition end time-tag coarse time (system clock ticks 125MHz) register

### 1. Memory map summary

H/W Address | Type | Name | VHDL/Verilog prefix | C prefix
--- | --- | --- | --- | ---
0x0 | REG | Timetag seconds register (upper) | timetag_core_seconds_upper | SECONDS_UPPER
0x1 | REG | Timetag seconds register (lower) | timetag_core_seconds_lower | SECONDS_LOWER
0x2 | REG | Timetag coarse time register, system clock ticks (125MHz) | timetag_core_coarse | COARSE
0x3 | REG | Time trigger seconds register (upper) | timetag_core_time_trig_seconds_upper | TIME_TRIG_SECONDS_UPPER
0x4 | REG | Time trigger seconds register (lower) | timetag_core_time_trig_seconds_lower | TIME_TRIG_SECONDS_LOWER
0x5 | REG | Time trigger coarse time register, system clock ticks (125MHz) | timetag_core_time_trig_coarse | TIME_TRIG_COARSE
0x6 | REG | Trigger time-tag seconds register (upper) | timetag_core_trig_tag_seconds_upper | TRIG_TAG_SECONDS_UPPER
0x7 | REG | Trigger time-tag seconds register (lower) | timetag_core_trig_tag_seconds_lower | TRIG_TAG_SECONDS_LOWER
0x8 | REG | Trigger time-tag coarse time (system clock ticks 125MHz) register | timetag_core_trig_tag_coarse | TRIG_TAG_COARSE
0x9 | REG | Acquisition start time-tag seconds register (upper) | timetag_core_acq_start_tag_seconds_upper | ACQ_START_TAG_SECONDS_UPPER
0xa | REG | Acquisition start time-tag seconds register (lower) | timetag_core_acq_start_tag_seconds_lower | ACQ_START_TAG_SECONDS_LOWER
0xb | REG | Acquisition start time-tag coarse time (system clock ticks 125MHz) register | timetag_core_acq_start_tag_coarse | ACQ_START_TAG_COARSE
0xc | REG | Acquisition stop time-tag seconds register (upper) | timetag_core_acq_stop_tag_seconds_upper | ACQ_STOP_TAG_SECONDS_UPPER
0xd | REG | Acquisition stop time-tag seconds register (lower) | timetag_core_acq_stop_tag_seconds_lower | ACQ_STOP_TAG_SECONDS_LOWER
0xe | REG | Acquisition stop time-tag coarse time (system clock ticks 125MHz) register | timetag_core_acq_stop_tag_coarse | ACQ_STOP_TAG_COARSE
0xf | REG | Acquisition end time-tag seconds register (upper) | timetag_core_acq_end_tag_seconds_upper | ACQ_END_TAG_SECONDS_UPPER
0x10 | REG | Acquisition end time-tag seconds register (lower) | timetag_core_acq_end_tag_seconds_lower | ACQ_END_TAG_SECONDS_LOWER
0x11 | REG | Acquisition end time-tag coarse time (system clock ticks 125MHz) register | timetag_core_acq_end_tag_coarse | ACQ_END_TAG_COARSE

### 2. HDL symbol

→ | rst_n_i |  | Timetag seconds register (upper): |
→ | clk_sys_i |  | timetag_core_seconds_upper_o[7:0] | ⇒
⇒ | wb_adr_i[4:0] |  | timetag_core_seconds_upper_i[7:0] | ⇐
⇒ | wb_dat_i[31:0] |  | timetag_core_seconds_upper_load_o | →
⇐ | wb_dat_o[31:0] |  |  |
→ | wb_cyc_i |  | Timetag seconds register (lower): |
⇒ | wb_sel_i[3:0] |  | timetag_core_seconds_lower_o[31:0] | ⇒
→ | wb_stb_i |  | timetag_core_seconds_lower_i[31:0] | ⇐
→ | wb_we_i |  | timetag_core_seconds_lower_load_o | →
← | wb_ack_o |  |  |
← | wb_stall_o |  | Timetag coarse time register, system clock ticks (125MHz): |
|  |  | timetag_core_coarse_o[27:0] | ⇒
|  |  | timetag_core_coarse_i[27:0] | ⇐
|  |  | timetag_core_coarse_load_o | →
|  |  | Time trigger seconds register (upper): |
|  |  | timetag_core_time_trig_seconds_upper_o[7:0] | ⇒
|  |  | Time trigger seconds register (lower): |
|  |  | timetag_core_time_trig_seconds_lower_o[31:0] | ⇒
|  |  | Time trigger coarse time register, system clock ticks (125MHz): |
|  |  | timetag_core_time_trig_coarse_o[27:0] | ⇒
|  |  | Trigger time-tag seconds register (upper): |
|  |  | timetag_core_trig_tag_seconds_upper_i[7:0] | ⇐
|  |  | Trigger time-tag seconds register (lower): |
|  |  | timetag_core_trig_tag_seconds_lower_i[31:0] | ⇐
|  |  | Trigger time-tag coarse time (system clock ticks 125MHz) register: |
|  |  | timetag_core_trig_tag_coarse_i[27:0] | ⇐
|  |  | Acquisition start time-tag seconds register (upper): |
|  |  | timetag_core_acq_start_tag_seconds_upper_i[7:0] | ⇐
|  |  | Acquisition start time-tag seconds register (lower): |
|  |  | timetag_core_acq_start_tag_seconds_lower_i[31:0] | ⇐
|  |  | Acquisition start time-tag coarse time (system clock ticks 125MHz) register: |
|  |  | timetag_core_acq_start_tag_coarse_i[27:0] | ⇐
|  |  | Acquisition stop time-tag seconds register (upper): |
|  |  | timetag_core_acq_stop_tag_seconds_upper_i[7:0] | ⇐
|  |  | Acquisition stop time-tag seconds register (lower): |
|  |  | timetag_core_acq_stop_tag_seconds_lower_i[31:0] | ⇐
|  |  | Acquisition stop time-tag coarse time (system clock ticks 125MHz) register: |
|  |  | timetag_core_acq_stop_tag_coarse_i[27:0] | ⇐
|  |  | Acquisition end time-tag seconds register (upper): |
|  |  | timetag_core_acq_end_tag_seconds_upper_i[7:0] | ⇐
|  |  | Acquisition end time-tag seconds register (lower): |
|  |  | timetag_core_acq_end_tag_seconds_lower_i[31:0] | ⇐
|  |  | Acquisition end time-tag coarse time (system clock ticks 125MHz) register: |
|  |  | timetag_core_acq_end_tag_coarse_i[27:0] | ⇐

### 3. Register description

### 3.1. Timetag seconds register (upper)

HW prefix: | timetag_core_seconds_upper
HW address: | 0x0
C prefix: | SECONDS_UPPER
C offset: | 0x0

8 upper bits of seconds counter. Incremented everytime the coarse counter overflows.

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | - | - | - | -

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
- | - | - | - | - | - | - | -

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
- | - | - | - | - | - | - | -

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
SECONDS_UPPER[7:0] |  |  |  |  |  |  |

- SECONDS_UPPER [read/write]: Timetag seconds

### 3.2. Timetag seconds register (lower)

HW prefix: | timetag_core_seconds_lower
HW address: | 0x1
C prefix: | SECONDS_LOWER
C offset: | 0x4

32 lower bits of seconds counter. Incremented everytime the coarse counter overflows.

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
SECONDS_LOWER[31:24] |  |  |  |  |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
SECONDS_LOWER[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
SECONDS_LOWER[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
SECONDS_LOWER[7:0] |  |  |  |  |  |  |

- SECONDS_LOWER [read/write]: Timetag seconds

### 3.3. Timetag coarse time register, system clock ticks (125MHz)

HW prefix: | timetag_core_coarse
HW address: | 0x2
C prefix: | COARSE
C offset: | 0x8

Coarse time counter clocked by 125MHz system clock.
Counts from 0 to 125000000.

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | COARSE[27:24] |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
COARSE[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
COARSE[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
COARSE[7:0] |  |  |  |  |  |  |

- COARSE [read/write]: Timetag coarse time

### 3.4. Time trigger seconds register (upper)

HW prefix: | timetag_core_time_trig_seconds_upper
HW address: | 0x3
C prefix: | TIME_TRIG_SECONDS_UPPER
C offset: | 0xc

8 upper bits of seconds used for timer trigger.

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | - | - | - | -

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
- | - | - | - | - | - | - | -

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
- | - | - | - | - | - | - | -

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
TIME_TRIG_SECONDS_UPPER[7:0] |  |  |  |  |  |  |

- TIME_TRIG_SECONDS_UPPER [read/write]: Time trigger seconds

### 3.5. Time trigger seconds register (lower)

HW prefix: | timetag_core_time_trig_seconds_lower
HW address: | 0x4
C prefix: | TIME_TRIG_SECONDS_LOWER
C offset: | 0x10

32 lower bits of seconds used for time trigger.

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
TIME_TRIG_SECONDS_LOWER[31:24] |  |  |  |  |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
TIME_TRIG_SECONDS_LOWER[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
TIME_TRIG_SECONDS_LOWER[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
TIME_TRIG_SECONDS_LOWER[7:0] |  |  |  |  |  |  |

- TIME_TRIG_SECONDS_LOWER [read/write]: Time trigger seconds

### 3.6. Time trigger coarse time register, system clock ticks (125MHz)

HW prefix: | timetag_core_time_trig_coarse
HW address: | 0x5
C prefix: | TIME_TRIG_COARSE
C offset: | 0x14

Coarse time counter clocked by 125MHz system clock.
Counts from 0 to 125000000.

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | TIME_TRIG_COARSE[27:24] |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
TIME_TRIG_COARSE[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
TIME_TRIG_COARSE[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
TIME_TRIG_COARSE[7:0] |  |  |  |  |  |  |

- TIME_TRIG_COARSE [read/write]: Time trigger coarse value

### 3.7. Trigger time-tag seconds register (upper)

HW prefix: | timetag_core_trig_tag_seconds_upper
HW address: | 0x6
C prefix: | TRIG_TAG_SECONDS_UPPER
C offset: | 0x18

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | - | - | - | -

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
- | - | - | - | - | - | - | -

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
- | - | - | - | - | - | - | -

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
TRIG_TAG_SECONDS_UPPER[7:0] |  |  |  |  |  |  |

- TRIG_TAG_SECONDS_UPPER [read-only]: Trigger time-tag seconds
  Holds time-tag seconds of the last trigger event

### 3.8. Trigger time-tag seconds register (lower)

HW prefix: | timetag_core_trig_tag_seconds_lower
HW address: | 0x7
C prefix: | TRIG_TAG_SECONDS_LOWER
C offset: | 0x1c

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
TRIG_TAG_SECONDS_LOWER[31:24] |  |  |  |  |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
TRIG_TAG_SECONDS_LOWER[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
TRIG_TAG_SECONDS_LOWER[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
TRIG_TAG_SECONDS_LOWER[7:0] |  |  |  |  |  |  |

- TRIG_TAG_SECONDS_LOWER [read-only]: Trigger time-tag seconds
  Holds time-tag seconds of the last trigger event

### 3.9. Trigger time-tag coarse time (system clock ticks 125MHz) register

HW prefix: | timetag_core_trig_tag_coarse
HW address: | 0x8
C prefix: | TRIG_TAG_COARSE
C offset: | 0x20

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | TRIG_TAG_COARSE[27:24] |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
TRIG_TAG_COARSE[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
TRIG_TAG_COARSE[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
TRIG_TAG_COARSE[7:0] |  |  |  |  |  |  |

- TRIG_TAG_COARSE [read-only]: Trigger time-tag coarse time
  Holds time-tag coarse time of the last trigger event

### 3.10. Acquisition start time-tag seconds register (upper)

HW prefix: | timetag_core_acq_start_tag_seconds_upper
HW address: | 0x9
C prefix: | ACQ_START_TAG_SECONDS_UPPER
C offset: | 0x24

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | - | - | - | -

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
- | - | - | - | - | - | - | -

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
- | - | - | - | - | - | - | -

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
ACQ_START_TAG_SECONDS_UPPER[7:0] |  |  |  |  |  |  |

- ACQ_START_TAG_SECONDS_UPPER [read-only]: Acquisition start time-tag seconds
  Holds time-tag seconds of the last acquisition start event

### 3.11. Acquisition start time-tag seconds register (lower)

HW prefix: | timetag_core_acq_start_tag_seconds_lower
HW address: | 0xa
C prefix: | ACQ_START_TAG_SECONDS_LOWER
C offset: | 0x28

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
ACQ_START_TAG_SECONDS_LOWER[31:24] |  |  |  |  |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
ACQ_START_TAG_SECONDS_LOWER[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
ACQ_START_TAG_SECONDS_LOWER[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
ACQ_START_TAG_SECONDS_LOWER[7:0] |  |  |  |  |  |  |

- ACQ_START_TAG_SECONDS_LOWER [read-only]: Acquisition start time-tag seconds
  Holds time-tag seconds of the last acquisition start event

### 3.12. Acquisition start time-tag coarse time (system clock ticks 125MHz) register

HW prefix: | timetag_core_acq_start_tag_coarse
HW address: | 0xb
C prefix: | ACQ_START_TAG_COARSE
C offset: | 0x2c

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | ACQ_START_TAG_COARSE[27:24] |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
ACQ_START_TAG_COARSE[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
ACQ_START_TAG_COARSE[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
ACQ_START_TAG_COARSE[7:0] |  |  |  |  |  |  |

- ACQ_START_TAG_COARSE [read-only]: Acquisition start time-tag coarse time
  Holds time-tag coarse time of the last acquisition start event

### 3.13. Acquisition stop time-tag seconds register (upper)

HW prefix: | timetag_core_acq_stop_tag_seconds_upper
HW address: | 0xc
C prefix: | ACQ_STOP_TAG_SECONDS_UPPER
C offset: | 0x30

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | - | - | - | -

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
- | - | - | - | - | - | - | -

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
- | - | - | - | - | - | - | -

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
ACQ_STOP_TAG_SECONDS_UPPER[7:0] |  |  |  |  |  |  |

- ACQ_STOP_TAG_SECONDS_UPPER [read-only]: Acquisition stop time-tag seconds
  Holds time-tag seconds of the last acquisition stop event

### 3.14. Acquisition stop time-tag seconds register (lower)

HW prefix: | timetag_core_acq_stop_tag_seconds_lower
HW address: | 0xd
C prefix: | ACQ_STOP_TAG_SECONDS_LOWER
C offset: | 0x34

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
ACQ_STOP_TAG_SECONDS_LOWER[31:24] |  |  |  |  |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
ACQ_STOP_TAG_SECONDS_LOWER[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
ACQ_STOP_TAG_SECONDS_LOWER[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
ACQ_STOP_TAG_SECONDS_LOWER[7:0] |  |  |  |  |  |  |

- ACQ_STOP_TAG_SECONDS_LOWER [read-only]: Acquisition stop time-tag seconds
  Holds time-tag seconds of the last acquisition stop event

### 3.15. Acquisition stop time-tag coarse time (system clock ticks 125MHz) register

HW prefix: | timetag_core_acq_stop_tag_coarse
HW address: | 0xe
C prefix: | ACQ_STOP_TAG_COARSE
C offset: | 0x38

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | ACQ_STOP_TAG_COARSE[27:24] |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
ACQ_STOP_TAG_COARSE[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
ACQ_STOP_TAG_COARSE[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
ACQ_STOP_TAG_COARSE[7:0] |  |  |  |  |  |  |

- ACQ_STOP_TAG_COARSE [read-only]: Acquisition stop time-tag coarse time
  Holds time-tag coarse time of the last acquisition stop event

### 3.16. Acquisition end time-tag seconds register (upper)

HW prefix: | timetag_core_acq_end_tag_seconds_upper
HW address: | 0xf
C prefix: | ACQ_END_TAG_SECONDS_UPPER
C offset: | 0x3c

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | - | - | - | -

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
- | - | - | - | - | - | - | -

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
- | - | - | - | - | - | - | -

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
ACQ_END_TAG_SECONDS_UPPER[7:0] |  |  |  |  |  |  |

- ACQ_END_TAG_SECONDS_UPPER [read-only]: Acquisition end time-tag seconds
  Holds time-tag seconds of the last acquisition end event

### 3.17. Acquisition end time-tag seconds register (lower)

HW prefix: | timetag_core_acq_end_tag_seconds_lower
HW address: | 0x10
C prefix: | ACQ_END_TAG_SECONDS_LOWER
C offset: | 0x40

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
ACQ_END_TAG_SECONDS_LOWER[31:24] |  |  |  |  |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
ACQ_END_TAG_SECONDS_LOWER[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
ACQ_END_TAG_SECONDS_LOWER[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
ACQ_END_TAG_SECONDS_LOWER[7:0] |  |  |  |  |  |  |

- ACQ_END_TAG_SECONDS_LOWER [read-only]: Acquisition end time-tag seconds
  Holds time-tag seconds of the last acquisition end event

### 3.18. Acquisition end time-tag coarse time (system clock ticks 125MHz) register

HW prefix: | timetag_core_acq_end_tag_coarse
HW address: | 0x11
C prefix: | ACQ_END_TAG_COARSE
C offset: | 0x44

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24
- | - | - | - | ACQ_END_TAG_COARSE[27:24] |  |  |

23 | 22 | 21 | 20 | 19 | 18 | 17 | 16
ACQ_END_TAG_COARSE[23:16] |  |  |  |  |  |  |

15 | 14 | 13 | 12 | 11 | 10 | 9 | 8
ACQ_END_TAG_COARSE[15:8] |  |  |  |  |  |  |

7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
ACQ_END_TAG_COARSE[7:0] |  |  |  |  |  |  |

- ACQ_END_TAG_COARSE [read-only]: Acquisition end time-tag coarse time
  Holds time-tag coarse time of the last acquisition end event