Chip Rockwell (R288F)

Pengantar

R288F adalah chip modem V.34 yang bekerja half duplex dan support untuk mengirim dan menerima data hingga kecepatan 33,6 KBps dengan tehnik half duplex mode V.34.

V.34 adalah tehnik untuk mengoptimalkan transfer data dengan kondisi line yang tersedia mulai dari kecepatan tertinggi 33,6 KBps hingga turun menjadi 2400 Bps. Dapat dioperasikan dengan PSTN (public switched telephone network)

Feature

• Half duplex fax/ modem dengan rata2 kecepatan hingga 33600 bps (V.34 HDX, V.17, V.29, V.27 ter dan V.21 channel 2)
• Full duplex data modem (V.21, V.23 dengan 75bps TX/1200 bps RX atau kebalikannnya)
• Mendukung HDLC pada seluruh kecepatan
• Serial synchronous data
• Parallel synchronous data
• Automatic Rate Adaption/ ARA (ARA tetap di dalam ROM dan dapat di adjust di RAM)
• Kompatibel dengan interface DTE dalam TTL dan CMOS
• Tegangann operasi +5V DC (700 mW/ normal, 65 mW/ sleep)
• Dikemas dalam PLCC 68 pin

Untuk literature selengkapnya dapat anda peroleh dalam format pdf di alamat url: http://www.nb.rockwell.com

© electmania, 2000

Mengenal Jenis-jenis Standarisasi Modem X2, K56Flex dan V.90

Belakangan ini di pasaran banyak beredar modem dengan spesifikasi yang membingungkan, pada saat penulisan ini, rata-rata modem yang ditawarkan mempunyai kemampuan transfer data hingga 56 KBps. Tentunya kehandalan dari modem tersebut harus di dukung oleh sistim jaringan (kabel telepon) yang baik, modem lawan yang berkecepatan tinggi dan lebar jalur data yang cukup (tidak terlalu padat, dengan memperhatikan ratio antara lebar jalur dan kapasitas modem yang online). Ketiga hal tersebut saling mempengaruhi satu dengan lainnya dalam kecepatan transmisi data. Bila salah satu darinya tidak mendukung, jangan harap modem yang cukup terbilang canggih tersebut akan dapat bekerja dengan sempurna.

Sebuah modem terdahulu yang berbasiskan protokol V.34 (33,6 KBps) sangatlah memboroskan uang. Saat ini terdapat 3 standarisasi modem 56K yang di-implementasikan oleh software (firmware) yang harus sesuai dengan ISP (penyelengara jasa internet). X2, merupakan standarisasi orisinil dari US Robotics (3COM) dan K56flex dari Rockwell. Sedangkan Lucent tidak kompatibel dengan kedua standar tersebut. Walaupun begitu Lucent dapat di upgrade menjadi standar V.90 dengan mem-flash memory ROM (EEPROM) di dalamnya, untuk menyesuaikan standar protokol yang digunakan pada ISP anda.

Cara Kerja Modem

Banyak keterbatasan untuk mendapatkan hasil yang maksimum dari modem 56K, untuk dapat bereaksi maksimum 56Kbps saat download data, ISP atau sumber lainnya harus memiliki true modem digital (modem yang bekerja secara digital penuh, bukan analog atau semi digital). Dalam hubungan point to point, jaringan sentral telepon (dalam hal ini PT. Telkom) juga harus bekerja secara digital dengan jalur yang bersih (tidak ada noise/ interferensi antar kabel).

Sebenarnya modem yang anda pakai saat ini merupakan device analog. Dengan rangkain A/D converter, signal tersebut di konversi menjadi signal digital lalu di transmisikan ke jalur telepon (digital) pada upstream data, dan diterima oleh modem ISP dan signal digital tersebut di konversi menjadi signal analog dengan D/A converter (lihat ilustrasi) di atas.

© electmania, 2000

This Technical White Paper discusses Windows* related design issues and compatibility requirements for modularized Audio Codec ’97 (AC ’97) subsystems called the Audio/Modem Riser (AMR) or the Mobile Daughter Card (MDC). Intel provides the AC ‘97 specification for adding analog codecs to a system board chipset, and a specification for AMR. There is diversity in system board chipsets and codecs that will support AC ‘97, and in AMR or MDC subsystems that use these codecs. Ensuring that the correct drivers are loaded is a significant issue. AMR was not designed for use as an add-in card. However, it can be used like one. PC manufacturers must be aware of the potential for problems if they do not exercise strict controls over system configurations. An AMR board must be used with a specific system board and BIOS. The Audio/Modem Riser is supported by utilizing the Plug and Play system design methodology. The AC ’97 codecs on an AMR device are attached to the system board chipset, which is exposed as a PCI bus device. One of the solutions outlined below must be used to present unique subsystem IDs and device IDs on the PCI bus for the combination of system board chipset, BIOS, and AC ‘97 device(s) in order to support Plug and Play for Windows. 2. AC ‘97 ID Space The PCI specification allows for two 16 -bit sets of Vendor Specific ID’s. The BIOS must read the codec’s VID1 and VID2 and use them as reference into a lookup table to determine: 1. Subsystem Vendor ID (number assigned to the AMR or baseboard manufacturer by the PCI SIG) and 2. Subsystem ID (AMR and/or codec device ID) The Subsystem Vendor ID (SSVID) and Subsystem ID (SSID) must be programmed for proper device driver enumeration and loading. For the audio function, programming the codec VID2 value into the Subsystem ID register is sufficient to fulfill step 2, above. However, for modem riser SKUs the codec ID is not sufficient and the OEM must provide a unique identification number for the Subsystem ID. Reg Name D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Default 7Ch Vendor ID1 F7 F6 F5 F4 F3 F2 F1 F0 S7 S6 S5 S4 S3 S2 S1 S0 na 7Eh Vendor ID2 T7 T6 T5 T4 T3 T2 T1 T0 REV7 REV6 REV5 REV4 REV3 REV2 REV1 REV0 na Table 1: Codec Vendor ID registers 2.1. Mechanisms to accomplish a modem riser enumeration The following addresses the basic Plug and Play (PnP) requirements for AMR modem implementations. Two alternative solutions are provided, using BIOS Fail Safe Mode, and using serial EPROM or shift-register. The key features of each are outlined.

R Page 3 The essential issue for the OEM and AMR vendor is to provide a unique identification (AMR Model No.) of the baseboard and AMR combination. Model information for AMR devices is available from the AMR vendor. However, this information is not readily available to the BIOS to correctly program the PCI Modem function of the core logic chipset. Given that the AMR is added during the final stages of manufacturing, the BIOS does not know which AMR is installed on the baseboard. 2.1.1. Use BIOS Fail Safe Mode One possible solution is to provide a BIOS setup option that is accessible only during the manufacturing process or during the Fail Safe recovery process. A setup option for the AMR ID will allow the manufacturing operator to enter the unique ID of the AMR module that has been stuffed in the baseboard. The ID can be retrieved from AMR PCB silkscreen or a similar mechanism. This ID number would then be used by the BIOS, during the AC ‘97 identification, to program the SSID field of the core logic chipset PCI AC ‘97 Modem Function. The PCI modem function can load a driver that is uniquely identified for the AMR device, when the unique AMR ID is programmed in the SSID and the OEM or AMR vendor ID provides the information for the SSVID. Key Features of this proposal · Fail Safe BIOS is available only during Manufacturing or by changing a jumper on the baseboard · User cannot change the AMR ID accidentally · The AMR is uniquely identified · Driver can properly load based on the SSVID and SSID information · OEM requires a manufacturing step change/addition · BIOS must add a new setup option · OEM software must be modified to configure OEM flash space (for AMR ID additional information) 2.1.2. Use Serial EPROM or Shift-Register AC ‘97 Modem Codecs today provide a number of GPIO pins in order to control external logic. A pair of these GPIO pins can be used to clock-in a unique ID from an external serial EPROM or Shift register. After the clocking procedure, the BIOS performs a modified AC ‘97 identification process, to program the SSVID and SSID registers of the core logic chipset modem function. Using the unique SSVID and SSID the PCI modem function can load a driver that is uniquely identified for the AMR installed in the system. The following figure displays a possible diagram of this implementation:

R Page 4 Figure 1: EPROM Diagram

Key Features of this proposal

· User cannot change the AMR ID accidentally

· The AMR is uniquely identified

· Driver can properly load based on the SSVID and SSID information

· BIOS is required to add a new identification algorithm

· AMR cost is increased by added logic

· Current AMRs may not use this methodology

· Most modem codec vendors must modify their devices to address this proposal

Pri. Codec SYNC BIT_CLK SDATA_OUT AMC/MC'97 Digital AC '97 Controller inside ICH RESET# SDATA_IN_0 S-EPROM GPIy Clock Data GPOx

Spread Spectrum Technology
Peer-to-peer communications model
12 signal lines used for Host processor interface
Signal reaches up to 4 km
9600 bps communication speed
Incorporates built-in over temperature protection circuit
Power down mode for reducing power consumption of internal signal amplifier
SPI compatible serial communication with host
5 V, 10 V  power supply required
Channel Access with unacknowledged services
Physical Layer Transceiver Interface

Copyright (c) 1998,  AMR Tech, Inc.
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Tel +82-2-3409-2470  Fax +82-2-497-3180 Email :  J.S.Lee marketing@amrtech.com