presto_en.pdf - 第89页

Page 89 The maximum frequency is 3MHz for the PRESTO programmer and 15MHz for FORTE. If the Ign ore FREQUENCY c ommands o ption is selected , the programmer applies on ly the frequenc y set by the user a nd ignores all…

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State of XSVF File

Implementation

The XSVF file support has been implemented in

accordance with the "XAPP503, Appendix B: XSVF File

Format" specification available at the Xilinx website with

the following limitations:

• XSETSDRMASKS, XSDRINC and XSIR2 commands are

not implemented.

• Only the XSVF file format is recommended for

programming the Xilinx XC9500/XV/XL families.

We seriously recommend using an SVF file for all

architectures except XC9500/XV/XL. For XC9500/XV/XL

programming, the use of the XSVF format is

recommended as the SVF format does not include the

XREPEAT command, which is necessary for XC9500/XV/XL

programming.

Warning: Executing a file containing the XREPEAT

command may be very slow.

8.1.3 Programming

Connector

The following table describes the functions of PRESTO's

and FORTE's pins for programming by means of the JTAG

interface.

PRESTO

FORTE

Function

VPP

SCK (System Clock)/User defined state

during file execution and after.

Not connected pin (key)

VDD

Feeding of I/O buffers

GND

Ground of I/O buffers

MOSI

JTAG TDI (Test Data In)

CLOCK

JTAG TCK (Test Clock)

MISO

JTAG TDO (Test Data out)

LVP

JTAG TMS (Test Machine State)

Table12: JTAG programming connector

8.2

Settings

This chapter explains the meaning of different settings in

Options ➙ Program Options.

8.2.1 Default TCK signal

frequency

This frequency of the TCK clock is used until the JTAG

Player reaches the first FREQUENCY command in the SVF

file or until the FREQUENCY with the "default" value is

reached.

The XSVF file format does not support the FREQUENCY

default command. Therefore frequency defined by

Default TCK Signal Frequency parameter is applied to

all operations.

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The maximum frequency is 3MHz for the PRESTO

programmer and 15MHz for FORTE.

If the Ignore FREQUENCY commands option is selected,

the programmer applies only the frequency set by the

user and ignores all FREQUENCY commands.

8.2.2 Fast Clocks Option

(FORTE only)

This option is available only for the FORTE programmer.

According to the JTAG specification, the signal at TDI is

sampled at TCK's rising edge. However, should a higher

frequency be required (around 5MHz or more), it may be

useful to change the moment of sampling from the rising

edge to the falling edge by shifting it by 1/2 of the TCK

period. To do so, choose Fast Clock Option.

8.2.3 RUNTEST without

run_count (SVF only)

The programmer should stay in the specified state for the

specified time and generate the clock signal on TCK while

executing an SVF file.

The specified time can be exceeded, but it slows the

programming process down. Even though it is not

supported by the SVF specification, many programmable

devices allow stopping the TCK clock during this time.

The programmer's ability to keep accurate time needs to

be considered. A high level of accuracy cannot be

achieved if the maximum frequency is used (the

programmer can guarantee respecting the min_time SEC

parameter only). A higher accuracy can be achieved with

slow clock (~100kHz). If the clock signal is not used at

all, the programmer is capable of following the min_time

SEC parameter almost exactly.

Three possibilities are available considering these facts:

• no clock on TCK

• slow clock on TCK (~100kHz)

• default speed clock on TCK

Example: "RUNTEST 3E-3SEC;" means "Generate clock on

TCK for at least 3ms".

8.2.4 RUNTEST Timing

Multiply (both SVF

and XSVF)

Recommended values:

• for accurate timing specified in the SVF or XSVF file:

0% (no added time)

• for XC9500(XL) family: 100% or more

• for Atmel AVR (e.g. ATmega128): 25%

8.2.5 RUNTEST with

run_count and no

timing

(bothSVFandXSVF)

This command should be interpreted as the minimum

frequency on TCK.

Yet some SVF file generators (such as Xilinx iMPACT, for

example) use this command as waiting time and assume

a frequency of 1MHz. For such cases the use of "interpret

as RUNTEST min_time with scale 1MHz" setting is

recommended.

JTAG Player Behavior When Reaching RUNTIME

Command With MINTIME Specification

(This concerns only SVF files as the RUNTEST alternative,

which is usable in XSVF XRUNTEST run_count cannot

specify time.)

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• The RUNTEST command containing run_count and

specifying min_time is executed at the currently

running TCK frequency. Therefore the command can

take much more time than what is specified in

min_time.

• The RUNTEST command containing run_count and

specifying max_time is executed at the currently

running TCK frequency. As the programmer cannot

respect the “deadline” specified in the max_time

parameter, this parameter is ignored.

8.2.6 VPP PRESTO / P

FORTE pin usage

while running test

(file) / after test

completion

The selection of the VPP / P pin function: TRST or SCK as

described in the SVF file or user-defined output levels.

(This is useful to keep the device in the reset state during

file execution.)

8.2.7 Default Settings

The JTAG Player features several default settings intended

primarily for use in connection with FORTE, but not with

PRESTO. Feel free to change these settings if the default

values do not suit your application.

Default Settings for FPGAs

Default TCK frequency: 15MHz; Ignore FREQUENCY

commands

Fast Clock Option (FORTE only): 5MHz and above

RUNTEST without run_count (SVF only): default

speed clock on TCK

RUNTEST timing multiply (both SVF and XSVF): 0%

RUNTEST with run_count and no timing (both SVF

and XSVF): interpret as RUNTEST min_time with scale

1MHz

VPP PRESTO / P FORTE pin usage while running test

(file): Tristate

VPP PRESTO / P FORTE pin usage after test

completion: Tristate

Default Settings for XC9500

Default TCK frequency: 5MHz; Ignore FREQUENCY

commands

Fast Clock Option (FORTE only): 5MHz and above

RUNTEST without run_count (SVF only): slow clock

on TCK (~100kHz)

RUNTEST timing multiply (both SVF and XSVF):

100%

RUNTEST with run_count and no timing (both SVF

and XSVF): interpret as RUNTEST min_time with scale

1MHz

VPP PRESTO / P FORTE pin usage while running test

(file): Tristate

VPP PRESTO / P FORTE pin usage after test

completion: Tristate

Default Settings for AVR:

Default TCK frequency: 1MHz; Ignore FREQUENCY

commands

Fast Clock Option (FORTE only): 5MHz and above

RUNTEST without run_count (SVF only): default

speed clock on TCK