ECE Department: University of Massachusetts, Amherst ECE 354 Lab 5: Data Compression

2 ECE 354 In this lab, you will…  Reuse Lab 4 and add additional components  Write both Verilog modules and C code Use custom Verilog modules along side the NIOS core Use C to interact with external Verilog modules

3 ECE 354 System Diagram Master BoardSlave Board Command Encoded Picture Data Monitor Camera Monitor RLE Encoder (Hardware) RLE Encoder (Hardware) NIOS Software NIOS Software RLE Decoder (Software) RLE Decoder (Software) BMP bit streamEncoded data NIOS Software Serial Port VGA Port

4 ECE 354 Overview  Implement new features by adding Verilog files into a current system. Buffer Modules (Input & Output) RLE Compression Module  Add SOPC components to interface with the new module Output PIO Input PIO Control PIOs  Write software to control and implement module usage

5 ECE 354 System Overview NIOS Processor (Software Code) FIFO Output Buffer (24 Bit Buffer) (Verilog File) RLE Compression (Verilog File) FIFO Input Buffer (8 Bit Buffer) (Verilog File)

6 ECE 354 RLE Hardware Block Structure and Integration NIOS core FIFO_send FIFO_recv RLE Unit ODATA_PIO[7:0 ] FIFO_IN_WRITE_REQ_PIO FIFO_IN_FULL_PIO IDATA_PIO[23:0 ] RESULT_READY_PIO FIFO_OUT_READ_REQ_PIO RLE_FLUSH_PIO FIFO_IN_ODATA[7:0] FIFO_IN_READ_REQ FIFO_IN_EMPTY RLE_OUT[23:0] RLE_DONE FIFO_OUT_FULL

7 ECE 354 FIFO Buffer  Saves data based on specified clock  Holds values in registers until requested  Outputs data in a specified way Same order in which it came into the buffer First In the buffer, first to come out (FIFO) Sends data only when requested by a signal  Used due to asynchronous signals and data sent from the software

8 ECE 354 Run Length Encoder  Takes data stream and records how many bits are the same  Input – 8 Bit data stream segments  Output – 24 Bit Data  How is more data bits compression? First bit – ID Bit (0 or 1) 23 bits – Number of 0 or 1s More of same value in sequence, more data is saved Worse Case - Interchanging data ( ) Use VGA data (1bit data) for compression and data exchange. More likely to get same value

9 ECE 354 Data Stream Format bit 1bit Original Data Stream Segment Encoded Data Stream Segment 8bit

10 ECE 354 Signals in Block Structure (To be added in SOPC)  ODATA_PIO[7:0] Output ports to send original bit-stream. 8-bit segment is sent at the same time  FIFO_IN_WRITE_REQ_PIO Assert write request signal for FIFO. FIFO stores input data when this signal is asserted  FIFO_IN_FULL_PIO Indicate FIFO is full. Sending picture data stream should wait until this signal is de-asserted  IDATA_PIO[23:0] Input ports to receive the encoded data 1 bit for bit ID, 23bits for representing number of bits. RLE can be implemented with smaller number of bits. However, in this lab, we use big enough bits to represent 640*480 picture  RESULT_READY_PIO Notify that there is an encoded data segment in the FIFO. Inverse of FIFO empty signal is used for this signal  FIFO_OUT_READ_REQ_PIO Assert Read request signal for FIFO. FIFO produces next data from the buffer when this signal is asserted  RLE_FLUSH_PIO Notify the end of the bit-stream. RLE produces a new encoded data segment immediately with current counting value

11 ECE 354 Signals in Block Structure (2)  FIFO_IN_READ_REQ Assert read request signal for FIFO  FIFO_IN_EMPTY Notify FIFO is empty. Therefore, RLE unit should wait until new data is available  RLE_OUT Pass the encoded data to the FIFO  RLE_DONE Notify encoding process is done, which means a new encoded data segment is ready. It is also used as a write assert signal for the FIFO  FIFO_OUT_FULL Notify FIFO is full. Therefore RLE unit should wait until this signal is de-asserted  FIFO_IN_ODATA[7:0] Provide a next bit-stream segment to RLE unit when FIFO_IN_READ_REQ is asserted

12 ECE 354 Process for Lab5  Take your LAB4  Create additional PIO with SOPC builder for your new hardware Check module system_0 in system_0.v Make sure new PIO ports are generated  Add your rle_enc.v and rle_fifo_8_24.v into your quartus project  Modify DE2_NET.v Instantiate your RLE unit and two FIFO modules Connect your hardware and SOPC core (system_0 u0) You need to write additional parameters for system_0 u0 to connect them with PIO

13 ECE 354 Contd.,  Full source code for 8 bit and 24 bit FIFO will be provided rle_fifo_8_24.v  Partial code for RLE unit will be provided Code for state transition will be given to you You will implement some parts that commented out You can modify if you have better idea  Run-length Encoding rle_enc.v  Top-level module DE2_NET.v You will need to modify to connect your new hardware

14 ECE 354 RLE completion and Simulation  Complete the rle_enc.v Simulate it if it is needed (optional)  Make sure your RLE module and file have the same name  Set RLE module as your Top-level design Open verilog file that has RLE module Menu->Project->Set as top-level entity  You need to generate input stimulus for RLE (optional to check RLE) Tutorial : tutorial_schematic.pdf Tutorial : tutorial_schematic.pdf  Open NIOS IDE Write code to control your hardware Write a function for decoding

15 ECE 354 How to Add/Wire New Modules  Top Module wires the components together with the SOPC DE2_NET.v is top module for the project Must add three components into the top module file 2 Buffers 1 RLE  To add a module, must follow certain format Module_File_Name Module_Name (.input1 (wire1).input2 (wire 2).output1 (wire3) );  system_0 is the SOPC core that generated by SOPC builder Look into system_0.v file in order to see the name of the generated PIOs

16 ECE 354 Verilog Simulation  A good debugging tool If your hardware doesn’t work correctly Sometimes it is hard to debug with LEDs and switches  Verilog language has ambiguity for simulation E.g) Race Condition Need to keep some guidelines to get correct result  Quartus has simulation capability

17 ECE 354 Race Condition  Produces different simulation result from real hardware  Keeping verilog design guideline is important clk) a = b; clk) b = c; Which statement will be executed first? An Example

18 ECE 354 Shift-Register in Verilog Incorrect implementation clk) begin shift_reg[2] = shift_reg[3]; shift_reg[1] = shift_reg[2]; shift_reg[0] = shift_reg[1]; end * ‘=‘ : Blocking Assignment * Value in shift_reg[3] will be assigned to shift_reg[0] directly Correct implementation clk) begin shift_reg[2] <= shift_reg[3]; shift_reg[1] <= shift_reg[2]; shift_reg[0] <= shift_reg[1]; End * ‘<=‘ : Non-Blocking Assignment * Updating will happen after capturing all right-side register values

19 ECE 354 Important Design Guideline for LAB5  Do not mix BA and NBA in the same always block  Use BA for combinational circuit in given design State transition  Use NBA for sequential circuit in given design Updating registers

20 ECE 354 Software Design  Use Altera functions to send/receive data inport() / outport() (IOWR/IORD)_ALTERA_AVALON_PIO_DATA()  Send data to be compressed while(buffer_not_full){ outport(data_pio_base, data);.....; }  Receive data from compression if(buffer_not_empty){ data = inport(dataout_pio_base);....; }

21 ECE 354 Software Design  Software (Master) must be able to decompress data Relatively easy Data tells you what to write Example: ( ) First Value = 1 Second Value = 7 Write 1, 7 times Output:

22 ECE 354 Tips  Go through the videos posted in the class website before starting the Lab-5.  Open SOPC builder in classic mode when adding the PIO to the system  Compressed Data is variable length for every picture Data could be compressed smaller, or expanded into larger data Assume data can be larger than picture data and Make compression data array to be bigger Make sure Master knows how big the data is Sequenced numbered packets End Packet Information Packet  Appendix attached at the end of the presentation describes the different signals used in FIFO buffer and RLE.

23 ECE 354 Summary  To implement hardware and software for RLE Encoding is done by Hardware GPIO is used Read/Write data from/to hardware is done by using ALTERA API Decoding is done by Software  The RLE implementation is added to Lab4 You send encoded picture data to the other board The data stream has variable length The data stream is decoded by software on receiving board Display the images before compression in slave board and the decoded image from the master.

24 ECE 354 Comments and/or Questions

ECE Department: University of Massachusetts, Amherst Appendix Signals and their Description

26 ECE 354 RLE Interface - Input  input clk,rst clk and reset  input recv_ready Connected with (!fifo_empty) of input side FIFO  input send_ready Connected with (!fifo_full) of output side FIFO  input [7:0] in_data Input data from input side FIFO 8 bit segment of original bit stream  input end_of_stream Indicate the end of bit stream Request flushing out the last segment

27 ECE 354 RLE Interface - Output  output [23:0] out_data Output data to output side FIFO [23] has bit ID, [22:0] has bit counting value  output rd_req Read request for input side FIFO  output wr_req Write request for output side FIFO

28 ECE 354 RLE Internal Signals  reg rd_reg connected to rd_req;  reg wr_reg Connected to wr_req;  reg [22:0] bit_count Stores number of same consecutive bit in bit stream value_type represent bit ID  reg value_type Bit ID

29 ECE 354 RLE Internal Signals  reg [7:0] shift_buf Store 8 bit segment of bit stream comes from input side FIFO Will be shifted out to calculate number of bits  reg [3:0] shift_count Current shift amount of shift_buf  reg new_bitstream Indicate new bit sequence is starting Current encoded data segment is passed to output side FIFO

30 ECE 354 RLE Internal Signals  reg [3:0] state Represent State. There are 9 states in total  reg [3:0] next_state Represent Next state

31 ECE 354 READ_INPUT shift_buf = in_data WAIT_INPUT rd_reg = 0 REQUEST_INPUT rd_reg = 1 shift_count = 0 COUNT_BITS Increase bit_count Set/reset new_bitstream SHIFT_BITS Shift sift_buf Increase shift_count Lookup new_bitstream COUNT_DONE wr_reg = 1 WAIT_OUTPUT wr_reg = 0 RESET_COUNT bit_count = 0 INIT bit_count = 0 shift_buf = 0 rd_reg = 0 wr_req_reg = 0 new_bitstream = 1 !recv_read !recv_read& end_of_stream& bit_count != 0 new_bitstream shift_count == 7 send_ready end_of_stream

32 ECE 354 RLE State in detail  INIT Initialize registers  REQUEST_INPUT Assert rd_req signal to FIFO by setting rd_reg FIFO takes rd_req signal at next clock  WAIT_INPUT 1 cycle stall is needed De-assert rd_req by setting rd_reg  READ_INPUT FIFO provides valid data after taking rd_req shift_buf stores 8 bit input data

33 ECE 354 RLE State in detail  COUNT_BITS Count number of consecutive bits in shift_buf If new type of bit starts, store bit ID in value_type register If current value_type and shift_buf[0] is not matched, notify current encoding is completed and new encoding will be started  SHIFT_BITS Right shift the shift_buf Increase shift_count Look up new_bitstream  COUNT_DONE Assert wr_req by setting wr_reg FIFO will take wr_req signal in next clock cycle

34 ECE 354 RLE State in detail  WAIT_OUTPUT 1 cycle stall is needed De-assert wr_req by setting wr_reg  RESET_COUNT Reset bit counting register after passing encoded data to output side FIFO