PCI Signal Descriptions

2 PCI Signal Descriptions 2.1 System Pins CLK Clock provides the timing reference for all transfers on the PCI bus. All PCI signals except reset and interrupts are sampled on the rising edge of the CLK signal. All bus timing specifications are defined relative to the rising edge. For most PCI systems the CLK signal operates at a maximum frequency of 33 MHz. To operate at 66MHz, both the PCI system and the PCI add-in board must be specifically designed to support the higher CLK frequency. A 66 MHz system will supply a 66 MHz CLK if the add-in board supports it, and supply a default 33 MHz CLK if the add-in board does not support the...

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PCI Bus Transactions

3. PCI Bus Transactions  Bus commands indicate to the target the type of transaction the master is requesting. Bus commands are encoded on the C/BE[3:0]# lines during the address phase. PCI bus command encodings and types are listed below, followed by a brief description of each. C/BE[3:0]# Command Types 0000 Interrupt Acknowledge 0001 Special Cycle 0010 I/O Read 0011 I/O Write 0100 Reserved 0101 Reserved 0110 Memory Read 0111 Memory Write 1000 Reserved 1001 Reserved 1010 Configuration Read 1011 Configuration Write 1100 Memory Read Multiple 1101 Dual Address Cycle 1110 Memory Read Line 1111 Memory Write and Invalidate The I/O Read command is used to read data from an agent mapped in I/O Address space. AD[31::00] provide...

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4 PCI Bus Timing Diagrams

4 PCI Bus Timing Diagrams 4.1 Basic Read/Write Transactions Figure 2 shows the timing of a typical read transaction — one that transfers data from the Target to the Initiator. Let’s follow it cycle-by-cycle. Figure 2: Timing diagram for a typical read transaction.Clock1: The bus is idle and most signals are tri-stated. The master for the upcoming transaction has received its GNT# and detected that the bus is idle so it drives FRAME# high initially. Clock 2: Address Phase: The master drives FRAME# low and places a target address on the AD bus and a bus command on the C/BE# bus. All targets latch the address and command on the rising...

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Configuration space decoding

5 Configuration space decoding PCI defines a third address space in addition to memory and I/O. This is called configuration space and every logical functiongets 256 bytes in this space. A function is selected for configuration space access by asserting the corresponding device’s IDSEL signal together with executing a Configuration Read or Configuration Write bus command. Configuration Transactions PCI-based systems require a mechanism that allows software to generate transactions to Configuration space. This mechanism will generally be located in the Host-to-PCI bridge. The specification defines an appropriate mechanism for...

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Arbitration process under PCI

6 Arbitration process under PCI: Since the PCI Bus accommodates multiple masters — any of which could request the use of the bus at any time — there must be a mechanism that allocates use of bus resources in a reasonable way and resolves conflicts among multiple masters wishing to use the bus simultaneously. Fundamentally, this is called bus arbitration. The Arbitration Process Before a bus master can execute a PCI transaction, it must request, and be granted, use of the bus. For this purpose, each bus master has a pair of REQ# and GNT# signals connecting it directly to a central arbiter as shown in Figure 11. When a master wishes...

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Error Detection and Reporting

7. Error Detection and Reporting Parity Generation & Detection — PAR and PERR# All bus agents are required to generate even parity over the AD and C/BE# busses. The result of the parity calculation appears on the PAR line. Even parity means that the PAR line is set so that the number of bus lines in the logical 1 state, including PAR, is even. All 32 AD lines are always included in the parity calculation even if they are not being used in the current transaction. This is another reason why the driving agent must always drive all 32 AD lines. All agents are required to have the ability to check parity. The agent driving the...

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Introduction to PCI protocol

Today’s computer systems, with their emphasis on high resolution graphics, full motion video, high bandwidth networking, and so on, go far beyond the capabilities of the architecture that ushered in the age of the personal computer in 1982. Modern PC systems demand high performance interconnects that also allow devices to be changed or upgraded with a minimum of effort by the end user. In response to this need, PCI (peripheral component interconnect) has emerged as the dominant mechanism for interconnecting the elements of modern, high performance computer systems. It is a well thought out standard with a number of forward looking...

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Format Short Message Service

At command for communications with SMS-CENTER. At hand phone GSM there is facility to data access applies serial connection, for data access is required by instruction sequence at interface hand phone. ETSI (European Telecommunication Standard Institute) that is the instruction standard in technical specification GSM. instruction phone is started with character AT and terminated with enter or 0Dh. Command received will be response with receiving of data ‘OK’ or ‘ Errors’. Applying AT Command important for SMS is: AT+CMGS : to send SMS AT+CMGL : to verify SMS AT+CMGD : to vanish SMS AT COMMAND for SMS usually followed by I/O started by units PDU. Streaming data or from SMS-CENTER must be in the form of PDU (Protocol Data Unit). PDU contains hexadecimal number what express language I/O. PDU...

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Power Supply derives 5 and 3.3V from USB port Circuit for Microcontroller

The circuit in the figure derives its power from a USB port and produces 5 and 3.3V supply rails for portable devices, such as digital cameras, MP3 players, and PDAs. The circuit allows the port to maintain communications while, for example, charging a lithium-ion battery. IC2 boosts the battery voltage, VBATT, to 5V, and IC3 buck-regulates that 5V output down to 3.3V. IC1, a lithium-ion battery charger, draws power from the USB port to charge the battery. Pulling its SELI terminal low sets the charging current to 100 mA for low-power USB ports, and pulling SELI high sets 500 mA for high-power ports. Similarly, pulling SELV high or low configures...

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Brightness Controller Circuit For Small Lamps and Leds

Switch-mode driven 1.5V bulb, Portable unit – 3V battery supply This device was designed on request; to control the light intensity of four filament lamps (i.e. a ring illuminator) powered by two AA or AAA batteries, for close-up pictures with a digital camera. Obviously it can be used in other ways, at anyone’s will.IC1 generates a 150Hz square wave having a variable duty-cycle. When the cursor of P1 is fully rotated towards D1, the output positive pulses appearing at pin 3 of IC1 are very narrow. Bulb LP1, driven by Q1, is off as the voltage across its leads is too low. When the cursor of P1 is rotated towards R2, the output pulses...

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Circuit Troubleshooting

Short notes about Circuit troubleshooting. - Check the circuit for mechanical failures, like disconnected wire, broken vias on the board, and connections between two adjacent vias which are not to be connected. - You should compare values of components and their connections with values and connections between components on the schematic. - Measuring DC voltages at certain points of the board, and comparing these values to the ones on the schematic. So, by knowing the operation of the circuit you start the process of elimination to find the “suspect” component. - If there are several “suspects”, and this is not a rare occurrence in complex devices, the testing is divided into groups of components, you start checking in reverse soldering order, this means that you start with components last...

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Lie Detector Circuit #2

This lie detector circuit can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth. It is not as sophisticated as the ones the professionals use, but it works. It works by measuring skin resistance, which goes down when you lie. Parts List: R1 – 33K 1/4W Resistor R2 – 5K Pot R3 – 1.5K 1/4W Resistor C1 – 1uF 16V Electrolytic Capacitor Q1 – 2N3565 NPN Transistor M1 – 0-1 mA Analog Meter MISC – Case, Wire, Electrodes (See Notes) Notes: The electrodes can be alligator clips (although they can be painful), electrode pads (like the type they use in the hospital), or just wires...

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LED or Lamp Pulsar Circuit

This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc. This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Q1 ensures current buffering, in order to obtain a better load drive. R4 & C1 are the timing components: using the values shown in the parts list, the total period is about 4 seconds. Parts: R1 = 4.7K R2 = 4.7K R3 = 22K R4 = 2.2M R5 = 10K R6 = 47R C1 = 1µF-63V Q1 = BC337 D1 = Red Led IC1 = LM358 Notes: The most satisfying results are obtained adopting for R4 a...

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Fuse Monitor Indicator

Description:The idea for this project may have come to me in a flash of inspiration, and its a very simple way to check if a fuse has blown without removing it from its holder. NotesThe simplicity of this circuit uses just two components, but with just one resistor and an LED this circuit gives visual indication of when a fuse has blown. LED1 is normally off, being “short circuited ” by the fuse, F1. Should the inevitable “big-bang” happen in your workshop then LED1 will illuminate and led you know all about it! Please note that the LED will only illumininatet under fault conditions, i.e. with a short circuit or shunt on the load. In...

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Sync-Tip Clamp/Restorer with AGC and De-Emphasis

This video circuit is Sync-tip Clamp/Restorer with AGC and De-emphasis. The active component used IC MAX7450. Below video clamp/restorer with layout and PCB...

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Broken Charger Connection Alarm Circuit

Detects if a device is not properly connected to its supply Suitable for battery chargers, portable appliance supplies etc. The above circuit can be useful to detect if the load of any battery charger or plug-in adapter supply is not properly connected. The load can be a set of batteries to be charged or any other type of battery or low dc voltage operated device. The circuit can safely operate over a 3 to 15V range and 1A max. Current, provided the supply voltage is about one volt higher than the voltage required by the load. The circuit is inserted between the supply and the load; therefore, until a trickle-charging current of at least...

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Analog Milliamp Meter Used as Voltmeter

A milliamp meter can be used as a volt meter by adding a series resistance. The resistance needed is the full scale voltage reading divided by the full scale current of the meter movement. So, if you have a 1 milliamp meter and you want to read 0-10 volts you will need a total resistance of 10/.001 = 10K ohms. The meter movement itself will have a small resistance which will be part of the total 10K resistance, but it is usually low enough to ignore. The meter in the example below has a resistance of 86 ohms so the true resistor value needed would be 10K-86 or 9914 ohms. But using a 10K standard value will be within 1% so we can ignore the...

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