HotRIO slave (with self-transmit)

This module implements the same functionality of the hotrio-slave with the added feature that it can be configured to self-transmit. If the slave_enable_i is connected to the rx_ready_o output of the pcs, it enables the module to start self-transmitting when the incoming signal is loss. Note that in this configuration, a clock selector must be used to change the tx PLL reference of the PCS from the clock recovered from the incoming data, to the local crystal.

Generics

Name	Description	Default value
HOTRIO_PCS_FREQUENCY	The frequency (in MHz) at which the packets are sent to the PCS. Used to calculate the number of clock cycles for the markers. This is used for the HotRIO master module.	125

Ports

Name	Mode	Description	Type
pcs_tx_clk125	IN	125MHz TX clock	std_logic
pcs_tx_rst125n	IN	125MHz TX reset	std_logic
pcs_rx_data_i	IN	Input PCS data, must be synchronized to the 125MHz TX clock	std_logic_vector(7 downto 0)
pcs_rx_kchar_i	IN	Input PCS k-character flag, must be synchronized to the 125MHz TX clock	std_logic
slave_en_i	IN	Slave module enable signal, active when ‘1’	std_logic
rx_address_i	IN	RX address input	std_logic_vector(7 downto 0)
tx_hotrio_packet_i	IN	Input hotrio packet	hotrio_packet_t
rx_hotrio_packet_o	OUT	Output hotrio packet	hotrio_packet_t
rx_packet_new_o	OUT	New RX packet flag	std_logic
rx_packet_valid_o	OUT	Valid RX packet flag	std_logic
pcs_tx_data_o	OUT	Output PCS data	std_logic_vector(7 downto 0)
pcs_tx_kchar_o	OUT	Output PCS k-character flag	std_logic
packet_sent_o	OUT	Packet sent flag	std_logic
slave_cnt_err_kchar_o	OUT	Slave count of k-character errors	std_logic_vector(CONFIG_DATA_WIDTH - 1 downto 0)
slave_cnt_err_data_o	OUT	Slave count of data errors	std_logic_vector(CONFIG_DATA_WIDTH - 1 downto 0)
slave_cnt_err_hrio_pid_o	OUT	Slave count of HRIO PID errors	std_logic_vector(CONFIG_DATA_WIDTH - 1 downto 0)
slave_cnt_err_parity_o	OUT	Slave count of parity errors	std_logic_vector(CONFIG_DATA_WIDTH - 1 downto 0)
slave_cnt_packets_received_o	OUT	Slave count of received packets	std_logic_vector(CONFIG_DATA_WIDTH - 1 downto 0)
slave_cnt_valild_packets_received_o	OUT	Slave count of valid received packets	std_logic_vector(CONFIG_DATA_WIDTH - 1 downto 0)
slave_sync_o	OUT	Slave synchronization flag	std_logic

* Defined in the Globals package

Dependencies

Name	Motivation
globals	Types definition and HotRIO constants.
signal_cdc	Used to synchronize the input reset
hotrio_master_tx	Used to self-transmit

Implementation details

This core consists of three main components: a HotRIO slave, a HotRIO master transmitter (tx), and a switch. The incoming PCS data is processed by the HotRIO slave, which decodes the data, synchronizes with it, and forwards it to the output. Simultaneously, the HotRIO master tx module generates HotRIO frames, populated with the input packets received by this module (tx_hotrio_packet_i). These two data streams are fed into a multiplexer (mux) controlled by the slave_en_i signal. When this signal is high, the output from the slave module is selected, otherwise, the output from the master is directed to the module’s output.