Presentation on theme: "2008 Developers Conference Taipei, Taiwan. An Introduction to Consumer Electronics Control (CEC) Quantum Data, Inc."— Presentation transcript:
2008 Developers Conference Taipei, Taiwan
An Introduction to Consumer Electronics Control (CEC) Quantum Data, Inc.
What is CEC? – Quick Facts CEC stands for Consumer Electronics Control. Its a one-wire bus (pin 13) that snakes through an HDMI system - allowing products to pass messages to one another. CEC runs at approx. 400Hz, so including flow control bits and idle timing requirements on the line, it can send approximately 30 bytes each second. Commands need to be very efficient.
CEC: A Bit of History In Europe, there was an analog predecessor to HDMI known as the SCART interface. Like HDMI, SCART carried audio and video signals through one cable. The SCART cable had a one- wire bus for controlling a home theater system. This was branded as AV.link by Philips, among others. This bus supported one touch play, standby, etc.
How To Find CEC Devices CEC is available in many HDMI products today! Limited multi-vendor interoperability. ManufacturerName PanasonicEZSync / HDAVI Control (USA), Viera Link (Japan) SonyBravia Theater Sync (USA), Bravia Link (Japan) SharpAQUOS FamiLink ToshibaCE-Link (USA), Regza Link (Japan) SamsungAnyNet+ LGSimpLink
What is the benefit of CEC? Todays HDMI systems are comprised of separate components (digital set top boxes, audio receivers/amps, a DVD player, etc.), which are not always easy to configure & operate. The general public has difficulty with the how/when/why to set up these devices in order to use them. The more devices, the more complex is the setup. CEC is a solution to this problem! CEC uses signal routing to allow devices to be configured across a system - rather than just point-to- point. Examples are one touch play and one touch record which greatly simplify the user experience.
CEC Messaging – Quick Facts CEC messages generally consist of two functional categories: – Request – asking another device(s) to take action or to give information (e.g. asking a device to play, go into standby, switch sources, or request a devices physical address). – Informative – status messages and messages describing where a devices is in a network (e.g. report physical address, report vendor ID). CEC messages can also be grouped in terms of the intended target device: – Directed Message - sent to a single CEC device. – Broadcast - sent to all devices in the CEC network. CEC messages can be up to 16 blocks total (including the header and opcode blocks). If they were longer, they would impede access to the CEC bus due to the speed of the bus. (Sending 16 blocks successfully takes about 0.4s). The shortest message that can be sent is the polling message, which is simply a start bit followed by a header block. Devices must respond to a message in 1 second or less, but the desired response time is 200 msec.
CEC Messaging – Blocks and Frames CEC Data Block Information Bits End of Message Acknowledgment CEC Header Block Logical Address of Initiator Logical Address of Destination End of Message Acknowledgment A CEC message block includes the 8 data bits as well as two extra bits: End of message – set to 0 for every block except the final block of the message where it is set to 1. Acknowledgement (ACK) – set to 1 for every block. CEC Frame Start Bit Header Block Optional Data Blocks Image View On – Routing Change - 5F Example Messages:
CEC at Work
CEC at Work – One Touch Play Image View On (40 04) DVD DTV AVR DVDGame SystemSTB-DVR 01 00:00: :00:00.00 PLAYER1->TV CEC CEC IMAGE VIEW ON 02 00:00: :00:00.60 PLAYER1->ALL CEC CEC ACTIVE SOURCE 03 00:00: :00:01.60 AUDIO->ALL CEC CEC REQUEST ACTIVE SRC 04 00:00: :00:06.20 PLAYER1->ALL CEC CEC ACTIVE SOURCE Active Source (4F ) DVDALL Request Active Source (5F 85) Request Active Source (5F 85) DVD DTVAVR Active Source (4F ) DVDALL Request Active Source (0F 85) ALLDTV Active Source (4F ) DVDALL 05 00:00: :00:01.60 TV->ALL CEC CEC REQUEST ACTIVE SRC 06 00:00: :00:06.20 PLAYER1->ALL CEC CEC ACTIVE SOURCE Device functions, actions, message simulation only, 3 ports AVR
CEC at Work – One Touch Play DTV AVR DVDGame SystemSTB-DVR 01 00:00: :00:00.00 TUNER->TV CEC CEC IMAGE VIEW ON 02 00:00: :00:00.60 TV->TUNER CEC CEC SET STREAM PATH 03 00:00: :00:01.60 TUNER->ALL CEC CEC ACTIVE SOURCE Image View On (30 04) Active Source (3F ) STB-DVRDTV STB-DVRALL Set Stream Path ( ) Ch. 2 Ch. 3 Ch. 4 DTV Remote
CEC at Work – Device Menu Control DTV AVR DVDGame SystemSTB-DVR Menu Status (Activate) (30 8E 00) User Control Released (03 45 XX) User Control Pressed (03 44 XX) STB-DVRDTV Menu Request (Activate) (03 8D 00) Menu Request (Deactivate) (03 8D 01) Menu Status (Deactivate) (30 8E 01) Ch. 2 Ch. 3 Ch. 4 Image View On (40 04) STB-DVR DTV Active Source (4F ) STB-DVRALL 01 00:00: :00:00.00 PLAYER1->TV CEC CEC IMAGE VIEW ON 02 00:00: :00:00.60 PLAYER1->ALL CEC CEC ACTIVE SOURCE DTV Remote 03 00:00: :00:00.00 TV->TUNER CEC CEC MENU REQUEST 04 00:00: :00:00.60 TUNER->TV CEC CEC MENU STATUS 05 00:00: :00:01.60 TV->TUNER CEC CEC USER CNTL PRESSED 06 00:00: :00:06.20 TV->TUNER CEC CEC USER CNTL RELEASED 07 00:00: :00:00.59 TUNER->TV CEC CEC MENU REQUEST 08 00:00: :00:00.50 TV->TUNER CEC CEC MENU STATUS
CEC at Work: One Touch Record AVR DVDGame System STB-DVR DTVSTB-DVR Record TV Screen (10 0F) Record Status [Recording Digital Service] (10 0A 02) Record ON [Digital Service ID] ( ) 01 00:00: :00:00.00 RECORDER->TV CEC CEC RECORD TV SCREEN 02 00:00: :00:51.10 TV->RECORDER CEC CEC RECORD ON 03 00:00: :00:00.20 RECORDER->TV CEC CEC RECORD STATUS DTV
CEC at Work – Deck Control DTV AVR DVDGame SystemSTB-DVR 01 00:00: :00:00.00 TV->PLAYER CEC CEC PLAY FORWARD 02 00:00: :00:00.60 PLAYER->TV CEC CEC PLAY STATUS Play [Forward] ( ) DTVDVD Deck Status [Play] (40 1B 11) DTV Remote Deck Control [Skip Forward] ( ) Deck Status [Skip Forward] (40 1B 17) 03 00:00: :00:00.00 TV->PLAYER CEC CEC SKIP FORWARD 04 00:00: :00:00.60 PLAYER->TV CEC CEC SKIP STATUS
CEC assumes that all AV source products in a system are directly or indirectly connected to a root display (DTV). HDMI connections form an upside-down tree, with a display as the root, switches as branches, and various source products as leaf nodes. There are two types of addressing: – Logical – Physical
Logical Addressing Logical addressing is what CEC uses to identify a specific instance of a specific device type. When messages are sent over CEC, the logical address identifies both the sender (Initiator) and intended receiver (Follower) of the message. Logical addressing is done with nybbles (4-bit numbers, allowing for addresses from 0-15). Because of this, the header blocks are simply in to, from format – the first four bits sent are the address of the initiator (or sender), while the latter four bits are the followers (receivers) address. CEC Header Block Logical Address of Initiator Logical Address of Follower End of Message Acknowledgment
Logical Addressing (continued) Logical addresses are split among device types: – 0 is a TV – 1,2 & 9 are recorders (HDD, DVD, BD, etc.) – 3,6,7 & 10 are tuner devices (i.e. set-top boxes) – 4,8 & 11 are players (DVD, VCR, Blu-Ray, etc.) – 5 is an audio system – 12 & 13 are reserved – 14 is a wild-card – 15 means Unregistered if its the initiator address, Broadcast if its the follower address.
Physical Addressing Physical addressing describes the topology, i.e. what devices are between the CEC device and the TV, and through what inputs it is connected. Physical addressing is a required feature for ALL HDMI devices (regardless of whether or not they support CEC), and is essential for routing control, among other things.
Physical Addressing Description A TV (that does not have HDMI outputs) will use physical address [ ]. Any device with an HDMI output will have an address that contains at least one non-zero number, which is grabbed from the HDMI vendor specific data block (VSDB) of the sink devices EDID. Devices with both a source and a sink must read the physical address from the EDID of the sink device that it is attached to, and configure its own EDIDs on its sink ports so that they contain the proper physical addresses.
CEC Addressing – Physical Addressing DTV AVR DVDGame SystemSTB-DVR PA 1100 PA 1200 PA 1300 PA 1000 PA
Physical Addressing – VSDB of EDID 1100
CEC Addressing – Logical Addressing DVD Game System STB-DVR LA 04 LA 05 LA 0 PA 0000 LA 0 PA 0000 LA 1100 LA 04LA 08 PA 1000 Polling Message (F5) UnregisteredAVR Report Physical Address (0F ) Report Physical Address (5F ) Polling Message (F4) Unregistered DVD Report Physical Address (4F ) Polling Message (F8) Unregistered Game System Report Physical Address (8F ) 01 00:00:10: :00:01:0100 TV->*ALL* CEC CEC REPORT PHYSICAL ADDRESS 02 00:00: :00:00:0060 UNREG->AUDIO CEC CEC CEC PING - NACK 03 00:00:11: :00:00:1000 AUDIO->*ALL* CEC CEC REPORT PHYSICAL ADDRESS 04 00:00:11: :00:00:0100 UNREG->PLAYER1 CEC CEC CEC PING - NACK 05 00:00:11: :00:00:0251 PLAYER1->*ALL* CEC CEC REPORT PHYSICAL ADDRESS 06 00:00:11: :00:00:0028 UNREG->PLAYER1 CEC CEC CEC PING AVR Polling Message (F4) Acknowledged PA :00:11: :00:00:0122 UNREG->PLAYER2 CEC CEC CEC PING - NACK 08 00:00:11: :00:00:0100 PLAYER2->*ALL* CEC CEC REPORT PHYSICAL ADDRESS AVRALL DVDALL Game SystemALL DTVAL L DTV
01 00:00:10: :00:01:0100 TV->ALL CEC CEC REPORT PHYSICAL ADDRESS 02 00:00: :00:00:0060 UNREG->AUDIO CEC CEC CEC PING - NACK 03 00:00:11: :00:00:1000 AUDIO->ALL CEC CEC REPORT PHYSICAL ADDRESS 04 00:00:11: :00:00:0100 UNREG->PLAYER1 CEC CEC CEC PING - NACK 05 00:00:11: :00:00:0251 PLAYER1->ALL CEC CEC REPORT PHYSICAL ADDRESS 06 00:00:11: :00:00:0028 UNREG->PLAYER1 CEC CEC CEC PING 07 00:00:11: :00:00:0112 UNREG->PLAYER2 CEC CEC CEC PING - NACK Polling Message (F3) Report Physical Address (3F ) Polling Message (F1) Report Physical Address (1F ) LA 03LA 01 DVD Game System STB-DVR DTV AVR Unregistered STB-DVR Unregistered STB-DVR LA 04 LA 05 LA 0 PA 0000 LA 0 PA 0000 LA 1100 LA 08 PA 1000 PA 1200 PA 1300 DTV CEC Addressing – Logical Addressing 08 00:00:11: :00:00:0100 PLAYER2->ALL CEC CEC REPORT PHYSICAL ADDRESS 09 00:00:11: :00:00:0600 UNREG->TUNER CEC CEC CEC PING - NACK 10 00:00:11: :00:00:0164 TUNER->ALL CEC CEC REPORT PHYSICAL ADDRESS 11 00:00:11: :00:00:0600 UNREG->RECORD CEC CEC CEC PING - NACK 12 00:00:11: :00:00:0000 RECORD->ALL CEC CEC REPORT PHYSICAL ADDRESS STB-DVRALL STB-DVRALL DTV: PA 000 LA 0 AVR: PA 1000 LA 05 DVD: PA 1100 LA 04 Game System: PA LA 08 STB-DVR: PA 1300 LA 03/LA 01
CEC Addressing – Sample Network
CEC Physical Layer
Physical Information CEC is pin 13 on the HDMI cable. It shares a common ground with DDC. CEC idles in a high-impedance state (the line shows a voltage between +2.5 and +3.63V). During a message, the line will be pulled down to between 0 and +0.6V (low-impedance).
Physical Information (continued) CEC supports nine devices on the bus simultaneously (potentially more if good cabling is used). The limitation is due to a network limit on capacitance of 7200pF (allowing for 100pF per device and 700pF per cable). However, there are only 15 valid CEC logical addresses, so having a limitation of nine devices would rarely be a problem in real-world applications. The CEC line is in use when there is a device pulling the line low. All timing is derived from the high to low transitions.
Physical Information – Bit Timing Start Bits Logical 0 and 1
CEC Message Waveform Max Rise Time = 250usecs Max Fall Time = 50usecs
CEC Bus Control
CEC Bus Control - Retransmission Retransmission can occur for many reasons: – A device could be holding the CEC bus low when the initiator expects it high, causing a bus error. – A device sends a message and does not receive the expected acknowledgement. – A device loses arbitration (retry). Retransmission should not occur if there is sufficient indication that the follower does not support the message being sent.
CEC Bus Control - Acknowledgement Directed messages – Intended for a single device – ACK is set as a logical 1 – Set to logical 0 by the follower to acknowledge Broadcast messages – Intended for all devices – ACK is set as a logical 1 – Must be kept as a logical 1 by all devices – A logical 0 is a NACK
CEC Bus Control - Acknowledgement DTV AVR DVDGame SystemSTB-DVR 01 00:00: :00:00.00 TUNER->TV CEC CEC IMAGE VIEW ON 02 00:00: :00:06.20 AUDIO->ALL CEC CEC REQUEST ACTIVE SRC Image View On (30 04) Request Active Source (5F 85) Request Active Source (5F 85) STB-DVRDTV AVR high low 0.6 ms1.5 ms Release bus to set Ack bit to 1 Pull down bus to Ack with 0 bit STB-DVR DTV 0.6 ms Release bus to set Ack bit to 1 AVR ALL Release bus Do nothing to acknowledge Directed Message Broadcast Message high low STB-DVR
CEC Bus Control – No Acknowledgement DTV AVR DVDGame SystemSTB-DVR 01 00:00: :00:00.00 TUNER->TV CEC CEC UNACKNOWLEDGED 02 00:00: :00:06.20 AUDIO->ALL CEC CEC UNACKNOWLEDGED Image View On (30 04) Request Active Source (5F 85) Request Active Source (5F 85) STB-DVRDTV AVR high low 0.6 ms1.5 ms Pull down to 0 to Nack STB-DVR DTV Release bus high low 0.6 ms Release bus to set Ack bit to 1 AVR DTV Do nothing to Nack Release bus to set Ack bit to 1 Broadcast Message Directed Message STB-DVR
CEC Bus Control - Arbitration Since CEC is a single wire for all devices, it is sometimes the case that two devices want to use the CEC line at the same time. Arbitration check begins with leading edge of start bit and continues to end of initiator address. Priority given to the device with the lowest logical address. The TV (logical address 0) has priority over all other devices. If a device is already using the CEC line, the devices that would like to use it must wait until signal free time has been met (the device has stopped using the line for a defined length of time). – At least 3 bit periods (7.2ms) in the case of a device trying to resend a message. – At least 5 bit periods (12.0ms) for a new device wishing to send a message – At least 7 bit periods (16.8ms) for the same device wishing to send a new message. Signal free time is defined from the START of the final bit being sent (the high to low transition).
CEC Bus Control - Arbitration Image View On (40 04) DVDDTV AVR DVDGame SystemSTB-DVR Active Source (4F ) DVD Get Menu Language (04 91) DTVSTB-DVR Record Status [Recording Digital Service] (01 0A 02) Record ON [Digital Service ID] ( ) 01 00:00: :00:00.00 PLAYER1->TV CEC CEC ERROR 02 00:00: :00:00.60 TV->PLAYER1 CEC CEC GET MENU LANGUAGE 03 00:00: :00:00.20 PLAYER1->TV CEC CEC IMAGE VIEW ON 04 00:00: :00:01.60 PLAYER1->ALL CEC CEC ACTIVE SOURCE Record TV Screen Record TV Screen (01 0F) Image View On 05 00:00: :00:06.20 TV->RECORDER CEC CEC UNACKNOWLEDGED 06 00:00: :00:06.11 TV->RECORDER CEC CEC RECORD TV SCREEN 07 00:00: :00:51.10 RECORDER->TV CEC CEC RECORD ON 08 00:00: :00:00.20 TV->RECORDER CEC CEC RECORD STATUS Signal Free Time >/= 3 bit times (~ 7.2ms) Retransmit Signal Free Time >/= 5 bit times (~ 12.0ms) New Message DTV
Verifying CEC Implementation
Verifying the CEC Implementation Compliance testing – In-house using compliance test tools – Plugfests (CEA and ETSI) – HDMI Authorized Test Centers Interoperability testing (multi-vendor) – In-house – Plugfests
Verifying the CEC Implementation Tools you will need – CEC debug tools used during development – CEC bus monitor – CEC compliance test application (Quantum Data Test Management Environment is the recommended test tool in the HDMI CTS) – Test fixtures
CEC Debug Testing – Error Simulator Sample screen of CEC debug test application. Enables: Simulation of acknowledgement failures Simulation of arbitration failures Ability to corrupt bits Modify timing parameters (Quantum Data CEC Controller)
CEC Debug Testing – Message Logger Sample screen of CEC Transaction logger: Logs CEC trans- actions during compliance test Logs CEC trans- actions during debug testing Shows detailed timing Shows acknow- ledgement and other errors (Quantum Data Auxiliary Channel Analyzer)
CEC Compliance Testing – CDF Entry Sample of a CEC compliance test application showing CDF definition: Enables importing CDF from comma separated value file for fast CDF definition Enables definition of CDF parameters for new devices through GUI Supports saving CDFs for later use (Quantum Data CEC Compliance Application)
CEC Compliance Testing - Test Initiator Sample of a CEC compliance test application showing test execution: Enables running of selective tests, or groups of tests Online help for test setup Tests run automati- cally without user interaction after test setup Results provided on display interface Comprehensive report for all tests that can printed or ed. (Quantum Data CEC Compliance Application)
For more information… Quantum Data has prepared an educational whitepaper and a video on CEC that provides some further examples:
Thank You… Presenter: Neal Kendall Technical consultant: Jeff Stenhouse Animation & Graphics: Robert Watson