In the middle of '80s, semiconductor unit of NEC Corporation, currently Renesas Electronics, started the study for increasing demands for automotive audio systems.[7]IEBus is introduced as a solution for the distributed control system.[8]: 18
In the late 1980s, several similar specifications, including the Domestic Digital Bus (D2B), the Japanese Home Bus (HBS),[9][10][11]
and the European Home System (EHS) are proposed by different companies or organizations. These were once discussed as IEC 61030,[12]
but it was withdrawn in 2006. IEBus is also a similar specification (refer to "Transfer signal format" section), but not listed in these criteria. As the result, IEBus becomes a de facto standard of car audio in Japan.[citation needed]
Regarding the Domestic Digital Bus (D2B), it is re-defined as D2B Optical by Mercedes-Benz independently.
As for Japanese Home Bus System (HBS), it is defined in 1988 as Home Bus System Standard Specification, ET-2101 by JEITA and REEA (Radio Engineering & Electronics Assiation) in Japan. It is being used by several Japanese air conditioner manufacturers (for example, M-Net from Mitsubishi[13] and the P1/P2 or F1/F2 bus from Daikin[14][15]). Fujitsu provided HBPC (Home Bus Protocol Controller) chip as MB86046B.[11] But it is unclear whether Fujitsu (currently, Cypress) still manufactures this HBPC LSI as of 2018. Mitsumi Electric provides the MM1007 and MM1192 driver ICs for HBS. The HBS specification is also discussed in the Echonet Consortium.[16][17][18][19][20]
In 2014, a utility model patent for protocol converter from HBS to RS-485 is granted in China as "CN204006496U."
[21]
Regarding the replacement of IEBus, a paper by Hyundai Autonet, currently Hyundai Mobis,[22]
describes as follows. "In communication methods for digital input capable amplifiers, Inter Equipment Bus (IEBus) was used in early times, but for now, Controller Area Network (CAN) is mainly used."[23]
Protocol overview
A master talks to a slave. Each unit has a master and a slave address register. Only one device can talk on the bus at any given time. There is a pecking order for the types of communications which will take precedence over another. Each communication from master to slave must be replied to by the slave going back to the master with acknowledge bits each of those show ACK or NAK.[4]: 10 If the master does not receive the ACK within a predefined time allowance for a mode, it drops the communication and returns to its standby (listen) mode.
Detailed specification of OSI model layer 2 is disclosed to licensees only, but protocol analyzers are provided from some test equipment vendors.[3][24]
In 2012, one of Chinese manufacturer's patent is granted as "CN202841169U".[25]
Physical layer (OSI model layer 1) specification overview
From μPD6708 data sheet.[4]: 7
and μPD78098B Subseries user's manual, hardware.[30]: 428
Communication system
Half-duplex asynchronous communication
Multi-master system
All the units connected to the IEBus can transfer data to the other units.
Broadcast communication function (communication between one unit and multiple units)
Normally, communication is individually carried out from one unit to another. By using the broadcast communication function, however, communication can be executed from one unit to plural units as follows:
Group broadcast communication: Broadcast communication to group units
Simultaneous broadcast communication: Broadcast communication to all units
Effective transmission rate
The effective transmission rate can be selected from the following three communication modes:
Mixture of the plural of modes in the same bus line is not allowed.
Correct communication between different base clock is not possible.
Mode
Maximum Number of Transfer Bytes (bytes/frame)
6.000000 MHz base clock
6.291456 MHz base clock
0
16
Approx. 3.9 kbit/s
Approx. 4.1 kbit/s
1
32
Approx. 17 kbit/s
Approx. 18 kbit/s
2
128
Approx. 26 kbit/s
Approx. 27 kbit/s
Access control
CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
The priority of occupying IEBus is as follows:
«1» Broadcast communication takes precedence over individual communication.
«2» The lower the master address, the higher the priority.
Communication scale
Number of units: 50 MAX.
Cable length: 150 m MAX. (when a twisted pair cable is used)
Load capacity: MAX. 8000 pF; between Bus+ and Bus−, (6.000000 MHz base clock) MAX. 7100 pF; between Bus+ and Bus−, (6.291456 MHz base clock)
P: Parity bit (1 bit); Even parity
A: Acknowledge bit (1 bit)
When A = 0: ACK
When A = 1: NAK
In broadcast communication, the value of the acknowledge bit is ignored.
N: Number of data bytes
Preparation period: The first or subsequent low-level (logic "1") period
Synchronization period: Next high-level (logic "0") period
Data period: Period indicating value of bit; ether low-level (logic "1") or high-level (logic "0")
Stop period: The last low-level (logic "1") period
Synchronization is done by each bit.
Time lengths of the synchronization period and data period are almost the same.
The time of the entire bits' and each bit's specification, related to the time of each period allocated to it, differ depending both on the type of the transmit bit and on whether the unit is the master or a slave unit.
Automotive manufacturers using IEBus
Each manufacturer has its own name, but it is not an alias of IEBus. Those are specifications of wire harness which comprise control cables based on IEBus, OSI model layer 3 and above communication protocol, audio cables, interconnection couplers, and so on.
Pioneer
Pioneer Corporation employed IEBus for its original branded car audio in early '90s. In its earlier stage, it was used just for control bus between the head unit in dashboard and the CD changer usually placed in trunk room. Nowadays, the specification includes connection between head units, navigation systems, rear speaker systems, and so on.
Pioneer Corporation pushed Toyota Motor Corporation to adopt IEBus as the genuine parts. In 1994, Toyota decided to employ IEBus for its genuine specification,[34]
but it is slightly different from that of Pioneer. It is named as AVC-LAN.
GR-SAKUKRA board and GR-SAKURA-FULL board[44]
are Renesas official promotion boards of RX63N chip, which enables IEBus mode 0 and 1, but not mode 2, i.e. not available for Toyota AVC-LAN.
They are an Arduino pin compatible low-price ones, suitable for hobbyists.
Their color of printed circuit board is SAKURA in Japanese, which means cherry blossom.
To evaluate IEBus, an external 5V bus interface transceiver (driver/receiver) IC extension is required.
The transceiver needs to correspond to 3.3V microcontroller (TTL logic voltage level) interface, otherwise 3.3V ↔ 5.0V level shifter is required. Dedicated terminals of RX63N chip themselves are 5V tolerant. For further information, refer to external links.
Most of IEBus controller LSIs require external dedicated bus interface transceivers (driver/receiver ICs). In its earlier stage, bus interface transceiver is included in the device, but it raised some restrictions to users.[46]
As is described in Pioneer's paper, external bus interface transceiver seems much stable.[32]
Some people tried to use TI's SN75176B for this purpose, but the result seems not to be reported.[47]
Each IEBus controller may have different implementation as long as the specification can be kept. As the result, host CPU load for each IEBus controller implementation differs.
Nowadays, there are thousands of microcontroller products to be list up, those which incorporate various different IEBus controller implementations. The following list is historically notable example.
Independent protocol controller products
μPD6708 (obsoleted); by Renesas, formerly NEC Electronics
μPD6708;[4]
the world's first "IEBus protocol controller" is usually thought as the golden protocol reference LSI.
This device supports full specification of IEBus mode 0, 1, and 2. It processes all the layer 1 and 2 of IEBus protocol by itself.
It is connected to a host microcontroller via 3-line serial interface.
6.291 MHz base clock is generated from 12.582 MHz external resonator.
This product contains IEBus interface transceiver.
μPD72042B (obsoleted); by Renesas, formerly NEC Electronics
μPD72042B;[48]
the second generation of IEBus controller supports mode 0 and 1.
This device performs all the processing required for layers 1 and 2 of IEBus protocol. The device incorporate large transmission and reception buffers, allowing host microcontroller to perform IEBus operations without interruption. It also contain an IEBus interface transceiver which allow the device to connect directly to the IEBus interface. It is connected to a host microcontroller via 3-line or 2-line serial interface.
6.291 MHz base clock is generated from 6.291 MHz or 12.782 MHz external resonator.
This product contains IEBus interface transceiver.
bus interface transceiver ICs
Each external bus transceiver (driver/receiver) IC is recommended to connect via 180 Ω protection resistors against both Bus+ and BUS- line.[46]
R2A11210SP (non promotion); by Renesas
R2A11210SP[49]
is a bus interface transceiver (driver/receiver) IC for IEBus with typically 30 mV hysteresiscomparator input.
HA12187FP (non promotion); by Renesas, formerly Hitachi
HA12187FP[50]
is a bus interface transceiver (driver/receiver) IC suitable for IEBus.
HA12240FP (current, as of 2018); by Renesas, formerly Hitachi
HA12240FP[51]
is a bus interface transceiver (driver/receiver) IC for IEBus with hysteresiscomparator input.
SN75176B[52]
is a general purpose bus transceiver with 50mV typically hysteresis comparator input. It looks like suitable for IEBus, but the result by a person is not reported.[47]
Microcontrollers incorporates IEBus controller
78K/0 Series μPD78098 Subseries (obsoleted); by Renesas, formerly NEC Electronics
μPD78P098A[53][54]: §20, pp.385–418 [55][56]
is an 8-bit single-chip microcontroller with on-chip 60K bytes UV-EPROM, 2K bytes RAM, and IEBus controller, which supports mode 0, 1, and 2, with full data link layer protocol support.
This is the world's first microcontroller which incorporates IEBus controller. Its IEBus controller function is almost the same as that of μPD72042B, but is located as memory mapped I/O called SFR (special function registers). 6.291 MHz base clock is generated from 6.291 MHz external resonator, while host CPU core and watch timer works 8.388 MHz generated from the same external resonator. External bus interface transceiver is required.
For programming, UV-EPROM erasor, UV-EPROM writer (27C1001A compatible), and writer adapter module are required.
78K/0 Series μPD78098B Subseries (obsoleted); by Renesas, formerly NEC Electronics
μPD78P098B[57]: §20, pp.428–461
is an 8-bit single-chip microcontroller with on-chip 60K bytes UV-EPROM, 2K bytes RAM, and IEBus controller, which supports mode 0, 1, and 2, with full data link layer support. It is probably a low noise variant of μPD78098 Subseries. Documents are refined.
17K Series μPD178098A Subseries (obsoleted); by Renesas, formerly NEC Electronics
μPD178F098[8][58]: §17, pp.367–422 [59]
is an 8-bit single-chip microcontroller for DTS (Digital Tuning System) of car radio, which incorporate simplified IEBus controller, 60K bytes Flash ROM, and 3K bytes RAM.
It does not support mode 0 and 2, but support mode 1 only. 6.291 MHz base clock is generated from 6.291 MHz external resonator, while host CPU core and watch timer works 8.388 MHz generated from the same external resonator. External bus interface transceiver is required.
78K/4 Series μPD784938 Subseries (obsoleted); by Renesas, formerly NEC Electronics
μPD78F4938[60]: §20, pp.467–510
is a 16-bit single-chip microcontroller for car audio, which incorporate simplified IEBus controller, 256K bytes Flash ROM, and 10K bytes RAM.
It does not support mode 0 and 2, but support mode 1 only. 6.291 MHz base clock is generated from 6.291 MHz external resonator. External bus interface transceiver is required.
V850 Family: V850/SB2 (non promotion); by Renesas, formerly NEC Electronics
V850/SB2[61][62][63]: §19, pp.541–599
is a long running 32-bit microcontroller employs IEBus controller with the 1st generation V850 CPU core.
Its IEBus controller is simplified from previous ones.[64]
It does not support mode 0 and 2, but support mode 1 only.[63]: 541
6.291 MHz base clock is generated from 6.291, 12.582, or 18.873 MHz external resonator.[63]: 257
This source clock is shared in the whole system in the chip including watch timer. A 32.768 kHz external crystal resonator is not used usually to reduce total BOM cost.
External bus interface transceiver is required, but external 5V I/O power supply is internally regulated to 3.3V or 3.0V,[63]: 517 which enables same voltage supply with external bus interface transceiver.
In addition, this product intended to design for ultra low-noise, which enables high RF receiving sensitivity for car radio.[65]: 41–44
In addition, starter motor mask time and electrical currentamplitude is well balanced.
LoL: on 03/23/2017 Rensas Electronics said "An external differential driver is required on the transmit/receive data line (not manufactured by NEC Electronics),"[64] but NEC Electronics is currently Renesas Electronics, and Renesas Electronics (formerly Hitachi) had been manufacturing "an external differential driver" named HA12240FP.[51]
In Japanese, it is said as "当社"[66]
which means Renesas Electronics itself.
V850 Family: V850E/Sx3-H (current, as of 2018); by Renesas, formerly NEC Electronics
V850E/SJ3-H and V850E/SK3-H[67]: §20, pp.973–1039
are 2nd generation V850 (E1 core) 32-bit microcontrollers.
Its IEBus controller is simplified, but supports both mode 1 and mode 2, not for mode 0.
External bus interface transceiver is required.
These products includes the V850E1 CPU core and peripheral functions. As for automotive network, these are equipped with IEBus and CAN (Controller Area Network) controllers.
V850 Family: V850ES/Sx2 (non promotion); by Renesas, formerly NEC Electronics
V850ES/SG3 and V850ES/SJ3 are 3rd generation V850 (ES core) 32-bit microcontrollers those contain IEBus controller.
V850 Family: V850ES/Sx3 (current, as of 2018); by Renesas, formerly NEC Electronics
V850ES/SG3[68]: §18, pp.632–697
and V850ES/SJ3[69]: §18, pp.660–725
are 3rd generation V850 (ES core) 32-bit microcontrollers.
Its IEBus controller is simplified, but supports both mode 1 and mode 2, not for mode 0.
External bus interface transceiver is required.
These products includes the V850ES CPU core and peripheral functions. As for automotive network, these are equipped with IEBus and CAN (Controller Area Network) controllers.
V850 Family: V850E2/Sx4-H (non promotion); by Renesas, formerly NEC Electronics
V850E2/SG4-H, V850E2/SJ4-H, and V850E2/SK4-H[70]: §30, pp.2195–2323
are 5th generation V850 (E2v3 core) 32-bit microcontrollers.
Its IEBus controller is simplified, but supports mode 1 and 2 with 32-byte buffers both for transmission and for reception.[70]: 2199 It also has automatic mechanism both for reissuing master requests when arbitration loss occurs; and for responding to slave status requests.[70]: 2199 Its supply clock is 8.000 MHz,[70]: 2199 which might not have compatibility with 6.291456 MHz base clock systems, almost all of car audio customer uses. It should be 8.388 MHz or nearest.
External bus interface transceiver is required.
These products includes the V850E2M CPU core and peripheral functions. As for automotive audio network, these are equipped with IEBus, CAN (Controller Area Network), LIN, PCM interface, MediaLB,[71][72]
and Ethernet controllers.
F2MC-16LX: MB90580C Series (current, as of 2018); by Cypress, formerly Fujitsu Microelectronics
MB90580C Series;[73]: §21, pp.345–408
F2MC-16LX 16-bit microcontroller of Cypress Semiconductor (formerly Fujitsu Microelectronics) has IEBus controller. It supports full feature of IEBus mode 0, 1, and 2, with 8-byte FIFO both for transmission and reception. Embedded peripheral resources performs data transmission with an intelligent I/O service function without the intervention of the CPU, enabling real-time control in various applications.
External bus interface transceiver is required.
M16C Family: M16C/50 Series (current, as of 2018); by Renesas, formerly Mitsubishi Electric
M16C/5L Group and M16C/56 Group[74]: §21.3.5, pp.486–487 [75]
is a 16-bit microcontroller with M16C/60 Series CPU Core.
UART2 can be used for IEBus controller as special mode 3 (IE mode).
External bus interface transceiver is required.
H8S Family: 2258 Group (current, as of 2018); by Renesas, formerly Hitachi
H8S/2258 and H8S/2256[76]: 316 [77][78]: §14, pp.481–546
is a long running microcontroller comprised internal 32-bit configuration H8S/2000 CPU core with 16-bit external bus controller. Its IEBus controller supports mode 0, 1, and 2 with 1 byte data buffer both for transfer and reception.
External bus interface transceiver is required.
RX Family: RX63N Group (current, as of 2018); by Renesas
RX63N[79]: §39, pp.1639–1680
is a recent 32-bit microcontroller. Its IEBus controller supports mode 0, and 1 (not 2). Arduino pin compatible low-price evaluation board, called SAKURA, is available for hobbyists.
^Goto, Masahiro; Tokuda, Akio; Tatemoto, Hirofumi (September 2011). "車載通信ネットワークの標準化の動向: FlexRayとMOSTを中心に" [Trend of Standardization in Automotive Communication Network System Case: FlexRay and MOST.] (PDF). Social System Study (in Japanese). 23: 159–173. ISSN1345-1901. Archived from the original(PDF) on 2018-02-14. Retrieved 2018-02-13.
^
Nakano, Kazukiyo; Kawakami, Koji; Tachi, Yuji (2002-04-10). "デュアル店舗機" [Vendor Showcase for Dual-Performance Stores] (PDF). Fuji Electric Journal (in Japanese). 75 (4): 244 (42). Fig.5 ISS: IE-BUS interface
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Kawata, Kazuhide (April 2014). "世界のカーラジオを変えた — DTS:μPD1700 / 17Kシリーズ物語"(PDF). Bulletin Encore. Paradime shift of car radio — DTS:μPD1700 / Development story of 17K Series (in Japanese). 84: 16–19.
^
Milivojević, Zoran (1994). "HOME BUS SYSTEM"(PDF). Facta Universitatis, Series: Electronics and Energetics. 7 (1): 53–60. ISSN2217-5997.
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Sugihara, K.; Kobatake, S.; Shirai, H.; Oowada, H.; Yoshitomi, K. (1989). "HBS-standard-compatible home bus protocol controller". IEEE Transactions on Consumer Electronics. 35 (3): 605–607. doi:10.1109/30.44324. ISSN0098-3063.
^"BS EN 61030:1993". ANSI. IEC. Specification for domestic digital bus (D2B) for audio, video and audiovisual systems (British Standard) Defines the modes of transmission, communication, protocols, addressing procedures, command language and electrical characteristics for home and small office use. Two-way intercommunication is also permitted with the Japanese Home Bus (HBS) and the European Home Bus (IHS)
^
MU, DANFENG (2014-01-13). "Protocol converter for monitoring of Daikin air conditioners". Espacenet. Summary Accordingly, the present invention for the presence of absence of the prior art, its main purpose is to provide an air conditioning monitoring Daikin protocol converter, which can effectively solve the prior Japanese unique Daikin air data communication transfer protocol Homebus and domestic common RS485 transmission protocol does not cause compatibility problems limit Daikin air-conditioning applications in intelligent remote monitoring and control.
^
angrycamel (2007-09-03). "IEBus Studio and Emulator". YouTube. Archived from the original on 2021-12-19. A screen cap of me using the IEBus emulator in conjunction with com0com and IEBus Studio.
^
Paret, Dominique (2007). "10.2". In Riesco, Roderick (ed.). Multiplexed networks for embedded systems: CAN, LIN, flexray, safe-by-wire…. Dunod, Paris: Wiley. p. 361. ISBN978-0-470-03416-3.
^ ab
Ikata, Yoshikatsu; Kurosaki, Masanori (1996-02-01). "The Development of the Interactive Pioneer Bus (IP-BUS)". SAE Technical Paper Series. 960122. doi:10.4271/960122. Abstract … We adopted the IEBus (Inter Equipment Bus) after above investigation. … 1. Separation of the IE-BUS driver/receiver: We developed the outside driver/receiver IC which was a built-in function of the original. This separation makes a system stable against vehicle noise and static electricity. Fig. 5 shows IEBus format …
AcuraZine.com Forums - (dead thread) Some results in recording data from the IEBus in an Acura TSX.
Marcin's Site - This site is great for learning more about the IEBus! He has really done a great job researching this protocol as well as developing one of the first boards that can talk on the bus using an ATMEGA8. (there are active forums on his site too, hereArchived 2007-06-18 at the Wayback Machine).
Louis Frigon (SigmaObjects.com) - A great write-up with schematics and source code that interfaces with the IEBus to trick the stock head unit into enabling aux input as it would for a CD changer. It is a great learning tool for how the IEBus protocol works just by looking through the well commented firmware source code. (Adapted from work done by Marcin at his site). (Broken link, please remove)