Maxim DS33Z41 Spezifikationen PDF herunterladen (Seite 9)

single-port device contains a JTAG test access-port controller, and because the BSDL language lacks the ability to define

multiple test access-port controllers. In the module, some pins such as address and data buses are tied together. The

JTAG pins are either tied in parallel or daisy-chained, as appropriate. More detail can be found in the device's data sheets.

To create the proper JTAG scan chain, four copies of the single-port version of the device need to be placed in the JTAG

chain. For example, if a DS21Q55 were placed on the board, the proper BSDL file would be the DS2155.

When using multichip modules in the JTAG chain, the design may need to be modified slightly to reflect the internal

connections present in the module. The amount of modification depends on whether the module is being used on a

physical tester or in conjunction with a simulation program. If the module is being used on a physical board, then the

implementation will only require that four copies of the single-port BSDL file to be placed sequentially in the JTAG test

chain. However, if the module is being used in a simulation, the implementation may be slightly more complex.

The first way to create a useful simulation model is to create a hierarchy in the design. The quad-port module is

considered to be a separate board made of four single-port devices. The connections are then made to match those

present inside of the module itself; these connections are detailed in the device data sheet. Another way is to directly

alter the netlist after the design is complete. This will essentially trick the simulation into believing that the quad-port

module is four separate single-port devices.

BSDL files are available on the Maxim website.

Q5. Is the DS2155 pin compatible with other Maxim SCTs?

A5. The DS2155 is closely pin compatible with DS2152/DS2154, DS21552/DS21554, and DS21352/DS21354 SCTs. The

biggest difference between the DS2152/DS2154, DS21552/DS21554, and the DS2155 or DS21352/DS21354 devices is

that the former devices all operate on 5.0V, while the latter operate on 3.3V (with 5.0V I/O tolerance). The DS2152/

DS2154 also do not support many of the pins/functions that the DS2155 has available. The DS21552/DS21554 and

DS21352/DS21354 offer the best compatibility, but there are some pins/functions that were changed between the

DS21x5y and the DS2155. The table below notes all the differences between the devices' pins.

Part

DS2152/DS2154 DS21552/DS21554 DS21352/DS21354 DS2155

Supply Voltage (V) 5.0 5.0 3.3 3.3

Pin 2 NC JTMS JTMS JTMS

Pin 3 8MCLK 8MCLK 8MCLK BPCLK

Pin 4 NC JTCLK JTCLK JTCLK

Pin 5 NC JTRST JTRST JTRST

Pin 7 NC JTDO JTDO JTDO

Pin 8 NC NC NC UOP0

Pin 9 NC NC NC UOP1

Pin 10 NC JTDI JTDI JTDI

Pin 14 TEST TEST TEST TSTRST

Pin 15 NC NC NC UOP2

Pin 23 NC NC NC UOP3

Pin 36 NC CI CI ESIBS0

Pin 54 NC CO CO ESIBS1

Pin 76 NC FMS FMS ESIBRD

Q6. Do the Maxim T1 devices support SLC-96?

A6. Because of the complexity of the SLC-96 specification, special synchronization circuitry, data registers, and status

registers were added to the T1 devices that allow the system designer to take advantage of the SLC-96 functionality.

Maxim T1 devices like the DS2141A, DS2151, DS2152, DS21352, DS21552, and DS2155 are capable of SLC-96 operation

in both transmit and receive directions. On the receive side, the devices are able to synchronize onto a received SLC-96

pattern and extract the message bits. On the transmit side, the devices are able to insert the SLC-96 synchronization

pattern and message bits. The devices also have the option to perform SLC-96 functions externally through hardware pins

or internally through software registers and interrupts.

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