README.md

OHWR General cores

General cores is a library of widely used cores but still small enough not to require a dedicated repository.

In modules/common there are general purpose cores:

• The package gencores_pkg provides the declarations of the components (this is not required, you can always directly instantiate the entities) but also some useful subprograms like functions for gray encode/decode, boolean conversions...

• The package matrix_pkg declares a 2d array of std_logic, and some subprograms to handle it.

• Edge detectors are provided by gc_posedge, gc_negedge, and gc_edge_detect.

• For clock-domain crossing or asynchronous signal register, use gc_sync. This is the basic synchronizer. If you also need an edge detector, use gc_sync_ffs. The other synchronizer gc_sync_register is deprecated. It can synchronize multiple signals at the same time but doesn't ensure coherency between these signals.

  The module gc_sync_edge provides a synchronizer with an (positive or negative) edge detector. The signal edge is always detected on the rising edge of the clock. This module is simpler than the gc_sync_ffs module.

  To pass words from one clock domain to another, you can use the module gc_sync_word_wr for writing data, and gc_sync_word_rd for reading data.

  To pass one pulse from one domain to another, use module gc_pulse_synchronizer or the version with resets gc_pulse_synchronizer2

  Module gc_async_signals_input_stage contains a complex handling for asynchronous signals (crossing clock domains, deglitcher, edge detection, pulse extension...)

• For reset generation, you can use gc_reset which generate synchronous resets once all the PLL lock signals are set. The module gc_reset_multi_aasd generate asynchronously asserted synchronously deasserted resets for multiple clock domains.

  The module gc_single_reset_gen is convenient to generate a single reset from multiple sources (like powerup signal and a reset button).

• Words can be packed or unpacked using the module gc_word_packer

• Module gc_i2c_slave provides a simple i2c slave. This module is used in gc_sfp_i2c_adapter to emulate an SFP DDM.

• The module gc_serial_dac provides an interface to a serial DAC.

• The module gc_rr_arbiter provides a round-robin arbiter amount an arbitrary number of requests. Similarly gc_arbitrated_mux provides a multiple channel tim-division multiplexr with round robin arbitration.

• The module gc_prio_encoder provides a combinational priority encoder.

• Module gc_bicolor_led_ctrl controls multiple bicolor leds, including the intensity.

• Module gc_big_adder provides a pipelined adder for wide numbers.

• Module gc_comparator provides a comparator with hysteresis.

• Module gc_moving_average compute the average of values over a sliding window. The size of the window is a power of 2.

• Module gc_crc_gen provides a generic parallel implementation of crc generator or checker.

• Module gc_dec_8b10b is an 8-bit to 10-bit decoder.

• Module gc_delay_gen is a delay line based on a pipeline, while module gc_delay_line implementation is based on a dual port RAM and provides a valid signal.

• Module gc_ds182x_readout provides a one-wire interface for temperature and unique id DS182X chips. It replaces the deprecated gc_ds182x_interface

• Module gc_dual_pi_controller is a two channels, proportional integral (PI) controller.

• To extend a pulse, several modules are provided:

  • gc_dyn_extend_pulse has an input for the length.
  • gc_extend_pulse has a fixed length.

• To deglitch a signal:

  • gc_dyn_glitch_filt accepts the minimum length as an input.
  • gc_glitch_filt is static: the length is provided as a parameter.

• Module gc_fsm_watchdog provides a simple watchdog.

• To mesure a frequency:

  • gc_frequency_meter provides a single channel counter.
  • gc_multichannel_frequency_meter is an optimized version for multiple channels.

In modules/genrams there are fifo and ram cores:

The convention is to use generic_xxx modules whose implementation may depend on the target.

• The package genram_pkg declares ram types, utility functions and the components.

• The package memory_loader_pkg declares functions that reads data from a file. They are useful to initialize the rams (and can be used for synthesis).

• The module generic_spram available for altera and for xilinx is a simple port synchronous ram.

• The module generic_simple_dpram available for altera and for xilinx is a dual port, dual clock, synchronous ram. The port A is write-only, the port B is read-only.

• The module generic_dpram available for altera and for xilinx is a dual port, dual clock, synchronous ram. Both ports are read/write.

• The module generic_dpram_mixed available for altera is a dual port, dual clock, synchronous ram. Both ports are read/write, and the size of the ports can be different.

• The module generic_sync_fifo is a synchronous fifo, with multiple flags available.

• The module generic_async_fifo is also a fifo with multiple flags available, but with different clocks for inputs and outputs.

• The module generic_async_fifo_dual_rst is also a fifo with multiple flags available, but with different clocks for inputs and outputs and with a reset input for each clock domain.

• The module generic_shiftreg_fifo is a synchronous fifo based on shift registers.

Directory modules/wishbone contains modules for wishbone.

• The package wishbone_pkg declare the records for the wishbone bus and some utilities.

• There are several peripherals:

  • wb_dma is a dma controller.
  • wb_dpram is a dual port ram controlled by two wishbone buses.
  • wb_gpio_port is a gpio controller.
  • wb_i2c_bridge is an i2c slave to wishbone master.
  • [wb_i2c_master]](modules/wishbone/wb_i2c_master) is an i2c master.
  • wb_irq contains irq controllers and generators.
  • wb_onewire_master is a onewire master.
  • wb_serial_lcd is an lcd controller.
  • wb_simple_pwm is a pwm controller supporting up to 8 channels.
  • wb_simple_timer is a simple counter.
  • wb_spi is an spi controller
  • wb_spi_flash is an spi flash controller
  • wb_uart is an uart.
  • wb_vic is the vectored interrupt controller.
  • wb_ds182x_readout is a direct interface to the digital thermometer.

• There are utilities to handle a wishbone bus:

  • wb_clock_crossing handle clock domain crossing.
  • wb_register add a pipeline register.

• There are modules to convert to a different bus

  • wb_async_bridge is a bridge with the AT91SAM9x CPU external bus interface.
  • wb_axi4lite_bridge is an axi4lite to wishbone bridge
  • wb16_to_wb32 is an adapter from a 16 data bit wishbone master to a 32 data bit wishbone slave. It uses an intermediate register. Refer to the module for how to use it.

• There are modules for axi4 bus

  • axi4lite32_axi4full64_bridge is a bridge from axi4full64 to axi4lite32. It was defined to interface with the Vivado PCI-e bridge and doesn't support all the axi4full features (in particular the burst accesses).

• There a modules to build a bus hierarchy:

  • wb_bus_fanout is a simple master to multiple slave decoder.
  • wb_crossbar is a generic multiple masters and multiple slaves crossbar.
  • wb_split is a very simple crossbar for 1 master and 2 slaves.
  • wb_remapper allows to remap addresses.
  • wb_conmax is an interconnect matrix, superseeded by the crossbar.
  • wb_metadata is a little helper to create metadata for the convention.
  • wb_indirect provides a wishbone master driven by an address and a data registers.