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fix

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Joris van Rantwijk 2024-10-12 10:55:41 +02:00
parent d9ff515723
commit 186d41df10
1 changed files with 9 additions and 7 deletions
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doc/fpga_firmware.md
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@ -219,13 +219,7 @@ It marks the point in the message sequence where an unknown number of messages h
The timetagger has 4 digital input signals.
If a rising or falling edge occurs on one of these signals, a timestamp is assigned to that event.
Timestamped events are transferred via DMA.
The 4 digital input channels are connected to the digital I/O connector of the Red Pitaya.
Digital input channels 0 to 3 correspond to pins `DIO0_P` to `DIO3_P`.
A 4-cycle glitch filter is applied to the digital input signals.
This filter rejects digital pulses shorter than 4 clock cycles (32 ns).
Timestamped event messages are transferred via DMA.
Messages are only emitted for _enabled_ event types.
Rising edges and falling edges can be separately enabled or disabled for each digital input channel.
@ -235,6 +229,14 @@ The messages are queued in a FIFO buffer inside the FPGA before being transferre
This FIFO is necessary to hold messages for a short time while the DMA engine sets up a DMA transfer.
It has room for 4096 messages.
## Digital input signals
The 4 digital input channels are connected to the digital I/O connector of the Red Pitaya.
Digital input channels 0 to 3 correspond to pins `DIO0_P` to `DIO3_P`.
A 4-cycle glitch filter is applied to the digital input signals.
This filter rejects digital pulses shorter than 4 clock cycles (32 ns).
## Output data format
The output from the timetagger is a sequence of 64-bit messages.