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# DVB FPGA
This project aims to implement RTL components for DVB-S2, initially focusing on
the transmission side.
|  |
| :---: |
| Functional block diagram of the DVB-S2 System from ETSI EN 302 307-1 V1.4.1 |
## Functional guidelines
* Behaviour should match exactly what GNU Radio produces for every combination of
parameters described on the DVB-S2 base spec (no extensions yet). This means
components should handle
* Frame types: Normal and short
* Constellations: 8 PSK, 16 APSK and 32 APSK
* Code rates: 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 8/9, 9/10,
* Components should also handle parameters changing on every frame, that is, they
should handle frame with config A then a frame with config B immediately
afterwards without requiring reset or wait cycles
* Use AXI-Stream interfaces
## Components' status
<!-- Definitions of each development stage: -->
<!-- * Simulation -->
<!-- * Data must match GNU Radio's output -->
<!-- * **Back to back data:** check no bubbles are inserted -->
<!-- * **Slow reader:** check that AXI backpressure works as expected -->
<!-- * **Slow writer:** check that output data is throttled correctly -->
<!-- * **Slow write and reader:** check AXI handshaking works as expected -->
<!-- * Hardware testing -->
<!-- * Check components is synthesized/implemented as expected by EDA tools -->
<!-- * Check for possible timing issues (too many logic levels, unintended latches, -->
<!-- etc) -->
<!-- [> * Still TBD. Basic idea is to stream data in/out via PCIe or DDR where the host <] -->
<!-- [> compares the actual and the expected results <] -->
<!-- [> * Might be interesting to have a generic GNU Radio to PCIe bridge so that one <] -->
<!-- [> could offload create a block diagram on GRC and run parts of it on a real <] -->
<!-- [> card <] -->
<!-- * Hardware integration -->
<!-- * Same as hardware testing but chaining components together to check it handles -->
<!-- multiple configs as expected -->
<!-- * Check that timing constraints are met when components are used together -->
### Core DVB-S2 components
| Component name | Simulation | HW testing | HW integration |
| :--- | :---: | :--: | :--: |
| Baseband scrambler | ✔ | TODO | TODO |
| BCH encoder | ✔ | TODO | TODO |
| Bit interleaver | ✔ | TODO | TODO |
| Constellation mapper | ✔ | TODO | TODO |
| LDPC Encoder | ✔ | TODO | TODO |
| Physical layer framing | ✔ | TODO | TODO |
### Performance and resource usage (WIP)
The [dvb_fpga/rtl/dvbs2_encoder.vhd](https://github.com/phase4ground/dvb_fpga/blob/master/rtl/dvbs2_encoder.vhd)
top level has been run through Vivado targeting a `xczu4cg-sfvc784-1LV-i` and
with a clock frequency of 300 MHz (both arbitrary). No timing issues were
reported and the resource usage post implementation is show below. Table below
assumes default values for generics, i.e., `POLYPHASE_FILTER_NUMBER_TAPS` =
`33`, `POLYPHASE_FILTER_RATE_CHANGE` = `2` and `DATA_WIDTH` = `32`.
| Component | LUTs | FFs | RAMB | DSPs |
| :--- | --: | --: | --: | --: |
| axi_baseband_scrambler | 277 | 46 | 0 | 0 |
| axi_bch_encoder | 1397 | 1380 | 0 | 0 |
| axi_ldpc_encoder | 1017 | 558 | 6 | 0 |
| axi_bit_interleaver | 339 | 262 | 10 | 0 |
| axi_constellation_mapper | 599 | 253 | 0 | 0 |
| axi_physical_layer_framer | 280 | 268 | 0 | 0 |
| + axi_plframe_header | 13 | 100 | 0 | 0 |
| + axi_physical_layer_scrambler | 39 | 70 | 0 | 0 |
| + dummy_frame_generator | 48 | 21 | 0 | 0 |
| polyphase_filter_i/q | 162 | 2168 | 0 | 64 |
| Register map | 586 | 318 | 0 | 0 |
| Debug infrastructure | 374 | 581 | 0 | 0 |
| Others | 1470 | 283 | 4 | 0 |
| **TOTAL** | **~6.5k** | **~6.1k** | **20** | **64** |
For details on what the "Others" row includes, see the [DVB-S2 Tx top level block
diagram][wiki] in the wiki.
## Running tests
Tests can be run locally or on a Docker container. Running locally will require
GNU Radio, VUnit and a VHDL simulator.
### Using Docker
Uses the same container used for CI
```sh
# Clone this repo and submodules
git clone --recurse-submodules https://github.com/phase4ground/dvb_fpga
cd dvb_fpga
# Run the tests
./misc/run_tests.sh
```
Arguments passed to `docker/run_tests.sh` will be passed to `run.py` and, by
extension, to VUnit (no environment variable is passed on though). This will
generate gnuradio_data (test data).
### Running locally
* Requirements
* GNU Radio
* A VHDL simulator
* [VUnit][vunit]
```sh
# Install VUnit
pip install vunit-hdl
# Clone this repo and submodules
git clone --recurse-submodules https://github.com/phase4ground/dvb_fpga
cd dvb_fpga
# Run the tests
./run.py
```
The first invocation of `run.py` will run GNURadio and create stimulus files.
To list tests use `./run.py -l`:
```sh
$ ./run.py -l
lib.axi_bit_interleaver_tb.data_width=8,all_parameters.back_to_back
lib.axi_bit_interleaver_tb.data_width=8,all_parameters.slow_master
lib.axi_bit_interleaver_tb.data_width=8,all_parameters.slow_slave
lib.axi_bit_interleaver_tb.data_width=8,all_parameters.both_slow
lib.axi_ldpc_table_tb.test_all_configs.back_to_back
lib.axi_ldpc_table_tb.test_all_configs.slow_master
lib.axi_ldpc_table_tb.test_all_configs.slow_slave
lib.axi_ldpc_table_tb.test_all_configs.slow_master,slow_slave
lib.axi_bch_encoder_tb.test_all_configs.back_to_back
lib.axi_bch_encoder_tb.test_all_configs.slow_master
lib.axi_bch_encoder_tb.test_all_configs.slow_slave
lib.axi_bch_encoder_tb.test_all_configs.both_slow
lib.dvbs2_encoder_tb.test_all_configs.back_to_back
lib.axi_ldpc_encoder_core_tb.test_all_configs.back_to_back
lib.axi_ldpc_encoder_core_tb.test_all_configs.data=0.5,table=1.0,slave=1.0
lib.axi_ldpc_encoder_core_tb.test_all_configs.data=1.0,table=1.0,slave=0.5
lib.axi_ldpc_encoder_core_tb.test_all_configs.data=0.75,table=1.0,slave=0.75
lib.axi_ldpc_encoder_core_tb.test_all_configs.data=1.0,table=0.5,slave=1.0
lib.axi_ldpc_encoder_core_tb.test_all_configs.data=1.0,table=0.75,slave=0.75
lib.axi_ldpc_encoder_core_tb.test_all_configs.data=0.8,table=0.8,slave=0.8
lib.axi_baseband_scrambler_tb.test_all_configs.back_to_back
lib.axi_baseband_scrambler_tb.test_all_configs.slow_master
lib.axi_baseband_scrambler_tb.test_all_configs.slow_slave
lib.axi_baseband_scrambler_tb.test_all_configs.both_slow
Listed 24 tests
```
## Running synthesis
Scripts are provided as an example to get things going, currently this has not
been tested in real hardware.
### Yosys
```sh
./misc/run_synth.sh
```
### Vivado
```sh
vivado -source ./build/vivado/build.tcl
```
[vunit]: https://vunit.github.io/
[wiki]: https://github.com/phase4ground/dvb_fpga/wiki#dvb-s2-tx
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