Abstract : CompactPCI Hot Swap veneer electrical design must meet the requirements of hot swap specification . To ensure that plug veneer , the CompactPCI bus does not have a greater impact , does not affect the CompactPCI bus, the correct data . Therefore, the electrical conducting hot swap single board design must take into account the electrostatic discharge , pre-charge , series match signal , the signal length limits and restrictions on the size of filter capacitor aspects . Hot Swap CompactPCI single board described in detail the typical structure , the physical connection process and electrical design elements . The application of electronic systems in general , if there circuit board hardware failure or software failure , usually before powering down the system and then repair or replace faulty equipment , so required a longer downtime. Very high reliability requirements in a number of high- reliability systems, allowed downtime , and downtime to replace a failed board or allow only very short downtime. For example, high- reliability communications , military applications, electronic systems in the event of a single board failure to require non-stop in the Zheng Ge system of allowing live Fault Ban and Charu pulled back plate , such systems typically support hot-swap system or high Jiaozuo Reliable system . First of all, the need for a hot swap system support hot-swap system platform , also need to support hot plug the card. Hot-plug system and are based on passive backplane bus platforms , in many passive backplane bus system , CompactPCI bus, with full support for hot swap specification , CompactPCI Bus Hot Swap system most widely used . This article focuses on single board CompactPCI Hot Swap Electrical Design Technology . 1 Hot Plug Technology Overview Hot swap plug that allows live working veneer , the basic aim is to live plugged veneer without affecting system operation for maintenance or re- configure the system board failure ; hot swap technology can provide access to a planned heat Plug device , allowing little or no need for non-stop operator involved in the case, fault recovery and system reconfiguration ; hot swap technology can provide high- reliability applications, when the veneer fails , the system in continuous operation To automatically isolate faults board . Hot-plug system level, from low to high divided into three types: basic hot swap systems, it has the performance of the basic hot swap requirements ; full hot swap system, which can be dynamically configured hot-plug veneer ; high Reliable system , which uses highly reliable hardware platform to achieve a higher level of control . Plug has three processes: the physical connection process, including the hot insert ( insert veneer runs in the system ) and heat pull ( pull operation in the system single board ); hardware connection process, the system to connect the hardware layer And disconnect ; software connection process , the system software layer that the connection and disconnect . The process can be further described with a set of states , although these states belong to the system level , but different connections associated with each other , shown in Figure 1 . For example, when there is no physical connection layer , the hardware connection layer can not produce the electrical connection ; when the veneer pulled from a running system , the software and hardware to connect automatically disconnect connection . In Figure 1 : P0: Veneer is not installed to the system , in a system isolation . P1/H0: Veneer slots have been inserted , all the pins are connected , but no power , CompactPCI bus is not active . At this point, the physical layer in the P1 state , state of the hardware layer in H0 . H1: Single- board electrical connection to the CompactPCI bus after initialization . H1F: veneer was ordered to power , initialization, but fails, or veneer failure is detected, disconnect from the CompactPCI bus . Not suitable for inserting this piece of veneer from the CompactPCI bus . H2/S0: single- board power , but the CompactPCI bus can only access the configuration space . At this point , the configuration registers have not yet configured . At this point, the hardware layer in the H2 state , the software layer in the S0 state . S1: single-board system has been configured . S2: the necessary software ( drivers, etc.) is loaded , single-board operating system and application software can be used . However, all the operations are not started . S2Q: this state with S2, but does not allow a new operation , veneer at rest . S3: veneer into the system , has been working . S3Q: software to complete the current operation , but not start a new operation, and veneer in a quiescent state . 2 CompactPCI Hot Swap veneer of a typical structure CompactPCI single board must include a CompactPCI bus interface devices , CompactPCI bus and PCI bus interface logic and timing completely phase . PCI bus interface devices commonly used are AMCC 's S5920, S5933, PLX 's PCI9052 , etc. , or use the PCI logic within the FPGA core (core). Of course, the interface device can also be combined and applied logic . CompactPCI Hot Swap veneer of a typical structure shown in Figure 2 . J1, J2 is the standard 2mm HM -type connector , which is CompactPCI hot swap specification is , CompactPCI single board is through these two connectors connected to the CompactPCI system platform . Among them, the J1 connector to connect CompactPCI bus length of the needle is graded (staged pin), which is divided into long needles, short needles , the long needle . Long needles are some of the power pin , shortest needle is BD_SEL # and IDSEL, other bus signals are in the long needle , and J2 are in the long needle . 3 CompactPCI Hot Swap veneer of the physical connection process CompactPCI Hot Swap veneer is the same physical connection process , shown in Figure 3 . Physical connection process is started from a single panel insert rails , to the shortest connection pin BD_SEL # date ; pull out the opposite process . Physical connection process is a mechanical connection process . In the process of mechanical connection , insert the veneer , the first electrostatic discharge , and then pre-charge , after the completion of such pre-charge bus to connect the signal pin , and finally BD_SEL # connection ; pull out the opposite process . Article ESD is charged to protect the hot swap plug in the process of veneer from static damage . In order to reduce pre-charge process is hot-swappable plug veneer veneer in the course of the impact of the bus signals ( capacitance effect). 4 hot swap veneer of Electrical Design Technology Single Board CompactPCI hot swap hot swap the electrical design must meet the standard "CompactPCI Host Swap Specificaiton" requirements. To ensure that plug veneer , the CompactPCI bus can not have a greater impact , can not affect the CompactPCI bus, the correct data must be considered from the following aspects . 4.1 Electrostatic Discharge Hot Swap veneer , electric plug in the process, to protect the veneer from static damage , discharge static electricity must be carried out . Must discharge in a single board design section , the slot in the CompactPCI chassis rails have a discharge . Thus, in the insert before the first electrostatic discharge ; to pull out before the first while to electrostatic discharge . Veneer of the PCB in hot swap the lower end of the outermost of three discharge design article : strip1, strip2, strip3. For example, a standard CompactPCI rear panel plug-in (height 233.5mm, length 80mm), should be designed to discharge section of the length of the three were 20mm, 27.5mm, 20mm, height 1.5mm. Which , strip3 directly connected with the case , strip1 and strip3 10MO resistor between the jumper , strip2 and digital connectivity through 10MO resistors shown in Figure 4 . Insertion , Strip1 first contacts with the discharge guide , followed strip2, finally strip3; pull out when the opposite. 4.2 Precharge Hot Swap Specification "CompactPCI Hot Swap Specification 2.1" provides hot swap plug veneer veneer process in order to reduce the impact on the bus ( capacitance effect) , must be on the veneer of the bus precharge signals , so that CompactPCI connector 's pin point the pre-charge voltage to 1.0V (± 0.2V). Insert the veneer , the CompactPCI bus signal lines in the connection before , so that a single board CompactPCI bus signal pre-charge to around 1.0V , so the bus signal lines to connect the moment of impact is small ; pull the veneer , the in CompactPCI bus signal line disconnected before making a single board CompactPCI bus signal pre-charge to around 1.0V , so that the bus signal line disconnected moments , the impact is small . Single- board need for pre-charge of CompactPCI bus signal that connector J1, J2 and CompactPCI interface device connected signal, including : AD0 ~ AD31, C/BE0 # ~ C/BE3 #, PAR, FRAME #, IRDY #, TRDY #, STOP #, LOCK #, IDSEL, DEVSEL #, PERR #, SERR #, RST #, AD32 ~ AD63, C/BE4 # ~ C/BE7 #, REQ64E, ACK64K, PAR64, need to pre-charge to around 1.0V . Veneer of pre-charge from the 5V power supply in a long needle , then through the voltage converter are pre- charge voltage Vps. Need to pre- charge signal , through a large resistor Rp pull to Vps pre-charge voltage ( see Figure 5). Choose the principle of resistance Rp , Rp the maximum should ensure Vps in 5ms , the need for pre-charge signal to the connector plug-in office to achieve the desired charging voltage 1.0V to 80%; Rp minimum should ensure the management of PCI devices Feet high when the low leakage current when not too large , pull-up resistor Rp generally not be less than 10kO. INTA #, INTB #, INTC #, INTD # / REQ # / PCI_RST # and other signals through 10kO pullup resistor to PCI interface device supply voltage (5V or 3.3V). 10kO pull-down resistor after BD_SEL # . 4.3 Series match In order to reduce the CompactPCI single- board the bus signal line branch (stub) on the impact of the bus , the bus signal must match the series resistance . Characteristic impedance of PCB wiring should be designed to 65O ± 10%, matching resistor is 10O. Need to match the resistor in series signals include : AD0 ~ AD31, C/BE0 # ~ C/BE3 #, PAR, FRAME #, IRDY #, TRDY #, STOP #, LOCK #, IDSEL, DEVSEL #, PERR #, SERR # , RST #, AD32 ~ AD63, C/DE4 # ~ C/BE7 #, REQ64 #, ACK64 #, PAR64 , and INTA #, INTB #, INTC #, INTD #. 4.4 Signal Line Length limit CompactPCI specification according to the requirements of veneer of pre-charge , series resistance of the Stub length must be restricted as shown in Figure 5 (PCB wiring characteristic impedance should be designed to be 65O ± 10%). Stub length of the shorter , the smaller the impact on the CompactPCI bus . In a single board , on the pre-charge signal from connector J1 or J2 to the CompactPCI interface device pins , the total length of the signal line should be less than 38.1mm, which , from the connector pins to the series resistance of the PCB wirelength Should be less than 15.2mm. Stub length of pre- charge resistor preferably zero , the longest no more than 2.5mm. 4.5 Determination of the size of filter capacitor Pre- hot-plug power supply veneer (early power, not controlled power supply ), when the veneer has existed in the swap . In the hot swap a single board , directly connected to the power management is not charged capacitor , inserted in the veneer process, will produce more in the inrush current , if the current is too large, may result in burning of connectors . To filter , usually in the power supply connector Department have received a filter capacitor . Therefore , in order to reduce the swap process, inrush current , filter capacitor must be limited to the total . Hot Swap specification according to the provisions of the pre- layer capacitance of the total power limit requirements are as follows : 5V, 3.3V, V (I / O) of the power planes , the total capacitance of not more than 8.8µF. +12 V,-12V power supply layer capacitance bus no more than 1.5µF. Single Board CompactPCI hot swap hot-plug electrical design must meet the standard "CompactPCI Host Swap Specification" requirements. To ensure that plug veneer , the CompactPCI bus can not have a greater impact , can not affect the CompactPCI bus, the correct data transmission , the electrical conducting hot swap single board design must take into account the electrostatic discharge , pre-charge , Signal series match , the signal length limits and restrictions on the size of filter capacitor aspects . I have designed a 16- slot CompactPCI over highly reliable platform , in hot-plug electrical design of veneer , to follow a few design principles discussed in this paper , the design of the veneer and the system can meet the technical requirements for hot-plug .