EECS150 Lab Lecture #61 AC97 PCM Audio EECS150 Fall 2007– Lab Lecture #6 Udam Saini 10/05/2007

EECS150 Lab Lecture #62 Today Checkpoint #1 Block Diagram Requirements AC97 Audio Administrative Info Reset & Timing Volume Controls Simulation Model 10/05/2007

EECS150 Lab Lecture #63 Checkpoint #1 (2) 10/05/2007

EECS150 Lab Lecture #64 Checkpoint #1 (3) Requirements Record and Play digital audio Use our audio fifo that we give you to store the audio bits. Holds only 8 seconds on audio. Implement Volume Controls Use the dipswitches to control the volume/mute levels. 10/05/2007

EECS150 Lab Lecture #65 Checkpoint #1 (4) Interfacing to external chips Exact Requirements Detailed timing and interface specifications If you get it wrong, who knows what happens? Datasheets Detailed specification document Includes EVERYTHING you need to know Simulation Often not possible We’re going to help you out here… 10/05/2007

6 Checkpoint #1 (5) To Do List (Not RTL or STD) Ensure AP_RESET_ is held long enough We’ll help you out on this one Continuously generate AP_SYNC Wait for CodecReady Initialize AC97 Control Registers Send Volume Commands Store PCM Data Play PCM Data EECS150 Lab Lecture #610/05/2007

7 AC97 Audio (1) EECS150 Lab Lecture #610/05/2007

3/11/20058 AC97 Audio (2) Serial Bit Stream You must generate a sync signal Two Parts to AC97 Command Data (Read/Write Registers) PCM (Wave) audio data The Chip LM4549A Audio Codec READ THE DATASHEET (Its short) EECS150 Lab Lecture #6

9 AC97 Audio (3) Bit serial transmission AP_SDATA_OUT is from FPGA to Codec AP_SDATA_IN is from Codec to FPGA Data transmitted in 256b frames 13 slots per frame Slot0 is 16b Slots1-12 are 20b Sync signal high (roughly) during Slot0 EECS150 Lab Lecture #610/05/2007

10 AC97 Audio (4) EECS150 Lab Lecture #610/05/2007

11 AC97 Audio (5) Slot0 - Tag Bit[15] - 1 is frame is valid Bits[14:11] - 1 if corresponding slot is valid Bits[10:2] - Not Used Bits[1:0] - ID, set to 2’b00 Slot1 - Register Address Slot2 - Register Data (for writes) Slots3&4 - PCM Audio Data EECS150 Lab Lecture #610/05/2007

12 AC97 Audio (6) EECS150 Lab Lecture #610/05/2007

13 AC97 Audio (7) Command Registers Control Volume/Mute Control PCM Audio Rate You’ll need to set this to FA0(4000) at reset EECS150 Lab Lecture #610/05/2007

14 AC97 Audio (8) EECS150 Lab Lecture #610/05/2007

15 Administrative Info (3) Deadlines Checkpoint 1 Design Review – Due next week in lab Checkoff – Due the following week in lab. Your design should be detailed enough that you could give your design to another group and have them implement it from scratch. GET YOUR CHECKPOINTS DONE EARLY Don’t wait for the deadline, you will fall behind EECS150 Lab Lecture #610/05/2007

16 Reset & Timing (2) LocalResetGen Generates resets for use with gated clocks Key components: Ability to hold reset high using a counter Shift register to cross clock domains Timeout in the event that the local clock dies Multiple reset outputs Outputs LocalClockReset – Resets the clock generator LocalRegReset – Resets all the registers EECS150 Lab Lecture #610/05/2007

17 Reset & Timing (3) AC97 Sync First high SAMPLE marks start of frame Not the first time you drive it high What’s the difference? Should be high for 16 cycles (Slot 0) This is CRITICAL Without proper sync the codec won’t work This signal is how the codec finds the start of the AC97 frame EECS150 Lab Lecture #610/05/2007

3/11/ Volume Controls (2) Features Inputs Speaker Volume/Mute Mic Volume/Mute Outputs Contents of the corresponding AC97 register We recommend modular design EECS150 Lab Lecture #6

19 Simulation Model (1) We built you a model LM4549ACodec.V This is for simulation ONLY It error checks the AC97 data Limitations This model is not perfect It may in fact have bugs Do not rely on only this model On board, SDATA_IN signal comes one cycle early. It’s a lot better than nothing EECS150 Lab Lecture #610/05/2007

20 Simulation Model (2) What does it do? Sends PCMInput.txt into your design Same directory as your ModelSim project Writes the output to PCMOutput.txt Displays control register writes Checks for timing errors Watches for common bugs GENERATES THE CLOCK EECS150 Lab Lecture #610/05/2007

21 Simulation Model (3) PCMInput.txt 10 hex digits per line PCMLeft is the first 5 digits PCMRight is the second 5 digits PCMOutput.txt Identical format If you do loopback the files SHOULD match Loopback is often a handy test EECS150 Lab Lecture #610/05/2007

22 And now… Read the datasheet Pages 2 and This will document EVERYTHING about the LM4549A It should be your first reference Don’t be afraid to test things We put a lot into that tester It’s not perfect. This is the best way to learn EECS150 Lab Lecture #610/05/2007

The Checkpoint (1) You have one week to complete this CP Design Reviews next week at the beginning of your lab section (remember Lab 5 checkoff) Bubble-and-arc diagram(s) for any FSM Block Diagram required EECS150 Lab Lecture #610/05/200723

The Checkpoint (2) Construction Demo circuit on board for check-off Remember you will be designing for CP2 concurrently as you finish CP1. Groups of two Start designing today! EECS150 Lab Lecture #610/05/200724