JP2000206203A - Boundary scan chain automatically connecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which can automate cutting and connecting a boundary scan chain on a mother board which are performed by connecting an option board. SOLUTION: This boundary scan chain automatically connecting device consists of a detour indicating part 3 of an option board 2 and a connecting/ cutting part 6 of a mother board 1. The connecting/cutting part 6 judges existance of the detour indicating part 3 which is mounted only in the case that a boundary scan chain is contained in the option board 2, cuts the boundary scan chain contained inside when the detour indicating part 3 exists, and connects the boundary scan chain contained inside when the detour indicating part 3 does not exist or the option board is not connected with a connector. As a result, the cutting and connecting of the boundary scan chain on the mother board 1 which are performed by connection of the option board 2 can be automated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motherboard having a plurality of connectors for connecting an option board including a boundary scan chain and another boundary scan chain including the connector. The present invention relates to a boundary scan chain automatic connection device for diverting a boundary scan chain to an option board or stopping the detour in accordance with the presence or absence of a boundary scan chain of an option board.

[0002]

2. Description of the Related Art Boundary scan is based on JTAG (Joi).
nt Test Action Group).

[0003] A boundary scan chain refers to an IC having a boundary scan mechanism conforming to this standard and an IC having a boundary scan mechanism connected in a daisy chain as shown in a schematic diagram of daisy chain connection in FIG.

When a test is carried out by adopting this standard, for example, a boundary scan chain is formed on a printed circuit board to be tested, and both ends of the chain are connected to one of edge connectors and to the other of the edge connectors. The test is performed by accessing the IC using the boundary scan control device. When this boundary scan chain was formed on a single printed circuit board such as a motherboard, there was no particular problem in conducting a test, but a connector for connecting an option board was provided between the boundary scan chain. If the option board is interrupted, the boundary scan chain on the motherboard may be bypassed to the option board's boundary scan chain, depending on whether the option board is connected or not and whether the connected option board has a boundary scan chain. The upper boundary scan chain needs to be connected to an option board without the boundary scan chain at the connector portion, or a method for preventing the option board from being disconnected because the option board is not connected is required.

This method is described below with reference to FIG. 4 which is a configuration change diagram using a short-circuit plug as an example of the prior art.

When the boundary scan chain on the motherboard 41 is connected to the option board without the boundary scan chain by the connector 43 or is disconnected because the option board is not connected, the short-circuit plug 44 is attached and the boundary scan chain is connected. When the option board 42 having the boundary scan chain is connected to the connector 43, the setting is changed so that the short-circuit plug 44 is removed and the boundary scan chain bypasses the option board 42.

[0007]

However, in the case of the above-mentioned method, since it is necessary to manually attach and detach the short-circuit plug, when the number of connected option boards is large, or when the configuration of the option boards differs from device to device, etc. However, there is a problem that the workability is remarkably reduced or a setting error occurs.

[0008] Therefore, an object of the present application is to cut and connect the boundary scan chain on the motherboard by connecting the option board, not by hand, but by automation.

[0009]

In order to solve the above problems, the present invention has proposed the following automatic boundary scan chain connection apparatus.

[0010] The automatic boundary scan chain connection device according to the present invention comprises an option board detour instruction unit and a motherboard connection / disconnection unit, and the connection / disconnection unit is mounted only when the option board includes a boundary scan chain. Determines the presence or absence of a detour indicator, cuts the internal boundary scan chain when there is a detour indicator, and internally has the boundary scan when there is no detour indicator or when no option board is connected to the connector Connect the chain. This makes it possible to automate disconnection and connection of the boundary scan chain on the motherboard by connecting the option board.

[0011]

FIG. 1 is a block diagram showing the principle of the present invention.

The present invention provides a connector 5 on a motherboard 1;
Connection / disconnection unit 6, boundary scan chain, detour instruction unit 3 on option board 2, card edge 4,
It consists of a boundary scan chain.

The detour instructing unit 3 is mounted only when the option board includes a boundary scan chain, and issues a detour instruction for the boundary scan chain on the motherboard 1 to the option board 2.

The connection / disconnection unit 6 is connected to the detour instructing unit 3 through the connector 5 and the card edge 4. The presence / absence of the detour instructing unit 3 is determined. The chain is cut, and if there is no detour instruction unit 3 or if the option board is not connected to the connector, the internal boundary scan chain is connected.

Next, the operation of the boundary scan chain automatic connection device of the present invention will be described with reference to the configuration diagram of FIG.

An option board including a boundary scan chain is provided with a detour instruction unit 3 in advance.

The connection / disconnection unit 6 determines the presence / absence of the detour instruction unit 3 of the option board 2, and disconnects the boundary scan chain contained therein when the detour instruction unit 3 is present.
As a result, the boundary scan chain bypasses the option board 2. When there is no detour instruction unit 3 or when the option board is not connected to the connector, the internal boundary scan chain is connected. As a result, the detour of the boundary scan chain to the option board is stopped. As described above, the disconnection and connection of the boundary scan chain on the motherboard by connecting the option board can be automated.

[0018]

Next, as an embodiment of the present invention, when a mechanism for instructing a detour can be mounted when the option board includes a boundary scan chain, the mechanism is mounted on the option board in advance, and the connector is connected to the connector from the motherboard side. Determine whether the connected option board has that mechanism, and if it has that mechanism, bypass the boundary scan chain on the motherboard to that option board, and connect the option board,
The operation of the automatic boundary scan chain connection device that can automatically disconnect and connect the boundary scan chain on the motherboard will be described with reference to the drawings.

First, the configuration of an embodiment of the present invention shown in FIG. 2 will be described.

The present invention comprises a motherboard 11 and an option board 12.

The option board 12 includes a boundary scan chain and a pull-up resistor 13 for pulling up an arbitrary pin on the card edge 14.

The pull-up resistor 13 is connected to the option board 1
2 is included only when a boundary scan chain is included, and functions as a mechanism for instructing a detour of the boundary scan chain on the motherboard 11 to the boundary scan chain on the option board 12.

The motherboard 11 includes a boundary scan chain, a pull-down resistor 16 for pulling down a pin of the connector 15 corresponding to the pin which has been pulled up on the card edge 14, and a bus driver 18 having the pull-down connected to a bus control port 17. .

The bus control port 17 controls the bus driver 18, connects a boundary scan chain through an input signal to the bus driver 18 in a state of logic "0", and inputs an input to the bus driver 18 in a state of logic "1". The signal is cut off, the boundary scan chain is cut, and the signal is diverted to the option board 12.

The bus driver 18 is a line drive circuit for transmitting a signal on a bus line.

Next, the operation of the automatic boundary scan chain connection apparatus shown in FIG. 2 will be described as follows.

First, when the option board 12 includes a boundary scan chain, an arbitrary pin of the card edge 14 is pulled up by the pull-up resistor 13.

The bus control port 17 of the bus driver 18 is connected to the connector 15 when no option board is connected, or when the option board is connected but the option board does not include a boundary scan chain, so that any pin at the card edge is pulled. When the bus driver 18 is not pulled up, the logic state becomes "0" while the pull-down state is maintained, and the boundary scan chain is connected to the bus driver 18 through a signal.

On the other hand, when the connector 15 includes a boundary scan chain and an optional board 12 in which an arbitrary pin of the card edge 14 is pulled up is connected, a bus connected to a pin of the connector 15 corresponding to the pin is connected. The control port 17 is pulled up to the logic state “1”, the bus driver 18 cuts off the signal, and the boundary scan chain on the motherboard 11 bypasses the boundary scan chain on the option board 12.

In the above embodiment, an example was described in which only one option board was connected to the motherboard.
If a plurality of option boards are connected, the same mechanism can be provided for each option board and each connector unit.

The present invention relates to a motherboard having a plurality of connectors for connecting an option board including a boundary scan chain and another boundary scan chain including the connector. An automatic connection device of a boundary scan chain for detouring or stopping the detour of the boundary scan chain to the option board according to the presence or absence of the boundary scan chain, and the boundary scan is performed when the option board includes the boundary scan chain. The present invention is applicable to an option board in which a mechanism for instructing a detour of a chain can be incorporated in advance.

Next, as another embodiment of the present invention, attention is paid to the ID code register of the IC with the boundary scan mechanism, and the detour switching which can detour the boundary scan chain for each option board, cancel the detour, or arbitrarily designate the detour can be performed. Boundary scan chain that can disconnect and connect the boundary scan chain by connecting the option board even if it is not possible to install a mechanism for instructing detours because the option board is a commercially available product etc. An embodiment of the automatic connection device will be described with reference to the drawings.

First, the configuration of another embodiment of the present invention shown in FIG. 3 will be described.

The present invention comprises a motherboard 21, an option board 22, an option board 23, and a personal computer 38.

The motherboard 21 includes a boundary scan chain, two connectors to which option boards are connected, a bus driver 24, a bus driver 25, a bus driver 26, a bus driver 27, and a flip-flop FF3.
2, FF33, FF34 and FF35. It should be noted that all the ICs having a boundary scan mechanism connected to the boundary scan chain have ID code registers.

Here, the bus driver and the flip-flop are a mechanism for bypassing the boundary scan chain for each option board or stopping the bypass. For example, the mechanism will be described focusing on the option board 23. When the data is set from the personal computer 38 to the FF 34 "1" and the FF 35 "0" through the test signal line, the bus driver 26 disconnects the signal and the bus driver 27 "Connecting" the signal bypasses the boundary scan chain. Similarly, FF34 “0”, FF3
5 By setting the data to “1”, the detour can be stopped.

The option board 22 includes a boundary scan chain.

The option board 23 is an option board that does not include a boundary scan chain.

The personal computer 38 is connected to the motherboard 21 and detours the boundary scan chain only to an optional option board to check for the presence of a boundary scan chain, to detour the boundary scan chain for each option board, or to detour. Used to specify or cancel.

Next, an embodiment in which the presence or absence of the boundary scan chain of any optional board on the motherboard can be checked based on the configuration diagram shown in FIG. 3 will be described below.

When data "0110" is transmitted from the personal computer 38 to the test signal line only to the option board 23 to bypass the boundary scan chain, the data is sequentially shifted from FF32 to FF33, FF34, and FF35, and the output of FF32 is output. Signal 28 is "0", FF
33 is "1", the output signal 30 of the FF 34 is "1".
Is "1", the output signal 31 of the FF 35 becomes "0", the bus driver 24 and the bus driver 27 are connected, the bus driver 25 and the bus driver 26 are disconnected, and only the option board 23 of the option boards is connected. The boundary scan chain can be bypassed.

Then, the personal computer 38 sends the IC to the IC having the boundary scan mechanism on the boundary scan chain.
RESET which is a signal defined in EEE1149.1
When the signal is transmitted, the contents of the ID code register are continuously output on the boundary scan chain, and only the option board 23 is output on the option board. Therefore, the ID of the output signal 37 of the output signal 37 from the personal computer 38 prior to the option board 23 is output.
After the signal of the code register is skipped, the 32-bit signal of one ID code register is read. If all of the signals are “0”, the option board 23 does not include the boundary scan chain or the option board 2
3 is not connected, and if not, it can be determined that the option board 23 including the boundary scan chain is connected. In this embodiment, the output before the option board 23 is the output of the IC 36 with the boundary scan mechanism.

Subsequently, by transmitting "1001" for bypassing the boundary scan chain only to the option board 22 from the personal computer 38 to the test signal line, the boundary scan chain is similarly bypassed only to the option board 22. When the RESET signal is transmitted to the boundary scan chain, the content of the ID code register is output to the boundary scan chain only for the option board 22 in the option board. After skipping the signal output before the minute, the 32-bit signal of one ID code register is read, and whether or not it is all "0" is determined.
It is possible to determine whether the option board 22 includes the boundary scan chain, and whether the option board 22 does not include the boundary scan chain or is not connected.

For a motherboard to which three or more optional boards can be connected, the transmission data is designated so that the boundary scan chain is bypassed from the personal computer 38 to only the optional board, and the optional data is bypassed. By reading the output signals for the boards and determining with the personal computer 38, it is possible to determine whether or not the option board is connected and whether or not the option board has a boundary scan chain.

Next, a description will be given of an embodiment in which the boundary scan chain can be diverted for each option board or the detour can be stopped or arbitrarily specified based on the above check results.

The data "1001" is transmitted from the personal computer 38 to the test signal line as data for bypassing the boundary scan chain on the motherboard 21 to the option board 22 but not to the option board 23. Then, the data is from FF32 to FF33, FF3
4, sequentially shifted to the FF 35, the output signal 28 of the FF 32 is “1”, the output signal 29 of the FF 33 is “0”,
34 is "0" and the output signal 31 of the FF 35 is "0".
Becomes “1” and the bus driver 24 and the bus driver 27
Is disconnected and the bus driver 25 and the bus driver 26 are connected, so that the boundary scan chain of the motherboard 21 bypasses the boundary scan chain of the option board 22 and does not bypass the option board 23.

It should be noted that even for a motherboard to which three or more option boards can be connected, the data transmitted from the personal computer 38 is diverted to the option board including the boundary scan chain, and if not, the detour is specified to be stopped. it can.

The present invention relates to a motherboard having a plurality of connectors for connecting an option board including a boundary scan chain and another boundary scan chain including the connector. An automatic connection device for a boundary scan chain for diverting or stopping the detour of the boundary scan chain to the option board according to the presence or absence of the boundary scan chain. Applicable when a mechanism for instructing a detour cannot be incorporated.

[0049]

According to the present invention, when an option board including a boundary scan chain is connected to a motherboard, the original boundary scan chain is cut off in order to bypass the boundary scan chain to the option board, or includes the boundary scan chain. When removing the option board from the motherboard or connecting an option board that does not include the boundary scan chain, there is no need to manually short the middle of the boundary scan chain so as not to bypass the boundary scan chain. At the time of shipment, the workability at the time of increasing or decreasing the option board is improved.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is a configuration diagram of another embodiment of the present invention.

FIG. 4 is a configuration change diagram using a short-circuit plug as an example of a conventional technique.

FIG. 5 is a schematic diagram of a daisy chain connection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motherboard 2 Option board 3 Detour indication part 4 Card edge 5 Connector 6 Connection / disconnection part 11 Motherboard 12 Option board 13 Pull-up resistor 14 Card edge 15 Connector 16 Pulldown resistor 17 Bus control port 18 Bus driver 21 Motherboard 22, 23 Option board 24, 25, 26, 27 Bus driver 28, 29, 30, 31 Output signal 32, 33, 34, 35 Flip-flop 36 IC with boundary scan mechanism 37 Output signal 38 Personal computer

Claims (3)

[Claims] 1. A motherboard having a plurality of connectors for connecting an option board including a boundary scan chain and another boundary scan chain including the connector, the connection of the option board and the boundary of the option board connected to the motherboard. This is an automatic boundary scan chain connection device for diverting or stopping the detour of the boundary scan chain to the option board according to the presence or absence of the scan chain.It is installed only on the option board including the boundary scan chain, and it is mounted on the boundary scan chain. A detour instructing unit for instructing the detour of the option board, and determining whether or not there is a detour instructing unit of the option board connected to the connector on the motherboard. A connection / disconnection unit for disconnecting the bypass switch and connecting the internal boundary scan chain when there is no detour instructing unit or when the option board is not connected to the connector. Connection device. 2. The detour instructing unit has a configuration in which an arbitrary pin on a card edge is pulled up, and issues a detour instruction on a boundary scan chain. The connection / disconnection unit is a connector corresponding to an arbitrary pin on a card edge. A pull-down pin connected to a bus control port to control a bus driver, and connecting / disconnecting an internal boundary scan chain by attaching / detaching an option board. Item 2. The automatic boundary scan chain connection device according to Item 1. 3. A motherboard having a plurality of connectors for connecting an option board including a boundary scan chain, and another boundary scan chain including the connector. This is an automatic boundary scan chain connection device for diverting the boundary scan chain to the option board or stopping the detour depending on the presence or absence of the scan chain.It detours the boundary scan chain for each option board and stops the detour An automatic boundary scan chain connection device, comprising: a detour switching means that can be specified or arbitrarily specified.