Deprecated: Method ReflectionProperty::setAccessible() is deprecated since 8.5, as it has no effect since PHP 8.1 in /var/www/html/plugins/system/falangdriver/falangdriver.php on line 534
怎样用示波器测量出 USB 总线上的差分信号？ - Bluetooth forum - bluetooth蓝牙技术
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怎样用示波器测量出 USB 总线上的差分信号？


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Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/cbPluginHandler.php on line 323
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2020-10-25 12:46 - 2020-10-25 12:46 #125 by btt
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USB 信号的测试分为 2 种情况： 第一种是需要进行符合 USB 组织定义 USB1.1/2.0 总线的物理层测试规范，只有通过 USB 一致性测试后方可打上 USB 标识。USB 物理层一致性测试分为很多个测试项目，主要是考察 USB 信号的信号质量如何，像 Signal Quality Test、 Droop & Drop Test、 Inrush Current Test、 HS Specific Tests、 Chirp Test 、Monotonic Test、 Receiver sensitivity Test、 Impedance Test （TDR） 等等。

　　第二种情况是仅观测 USB 总线上的信号，可以选择合适的差分探头连接到 D+， D-，直接进 行 USB 信号的观测。USB2.0 信号速度比较快，上升时间为几百皮秒，为了保证信号的包真度测试，需要选择大于 2GHz 的示波器和差分探头进行测试。
Last edit: 2020-10-25 12:46 by btt.

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/LegacyFoundationFunctions.php on line 234

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/LegacyFoundationFunctions.php on line 237

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/LegacyFoundationFunctions.php on line 239

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/LegacyFoundationFunctions.php on line 189

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/LegacyFoundationFunctions.php on line 237

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/LegacyFoundationFunctions.php on line 239

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Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/cbPluginHandler.php on line 323

Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/cbPluginHandler.php on line 323

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/src/Menu/AbstractMenu.php on line 164

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/LegacyFoundationFunctions.php on line 189

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/LegacyFoundationFunctions.php on line 237

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /var/www/html/libraries/CBLib/CB/Legacy/LegacyFoundationFunctions.php on line 239

Deprecated: Method ReflectionProperty::setAccessible() is deprecated since 8.5, as it has no effect since PHP 8.1 in /var/www/html/plugins/system/falangdriver/falangdriver.php on line 100

Deprecated: Method ReflectionProperty::setAccessible() is deprecated since 8.5, as it has no effect since PHP 8.1 in /var/www/html/plugins/system/falangdriver/falangdriver.php on line 100
mysqli object is already closed (500 Whoops, looks like something went wrong.)

Error

HTTP 500 Whoops, looks like something went wrong.

mysqli object is already closed

Exception

Error

in /var/www/html/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php (line 318)
  1. */
  2. public function disconnect()
  3. {
  4. // Close the connection.
  5. if (\is_callable([$this->connection, 'close'])) {
  6. $this->connection->close();
  7. }
  9. parent::disconnect();
  10. }
in /var/www/html/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php -> close (line 318)
  1. */
  2. public function disconnect()
  3. {
  4. // Close the connection.
  5. if (\is_callable([$this->connection, 'close'])) {
  6. $this->connection->close();
  7. }
  9. parent::disconnect();
  10. }
in /var/www/html/libraries/vendor/joomla/database/src/DatabaseDriver.php -> disconnect (line 496)
  1. *
  2. * @since 2.0.0
  3. */
  4. public function __destruct()
  5. {
  6. $this->disconnect();
  7. }
  9. /**
  10. * Alter database's character set.
  11. *
DatabaseDriver->__destruct()

Stack Trace

Error 
Error:
mysqli object is already closed

  at /var/www/html/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:318
  at mysqli->close()
     (/var/www/html/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:318)
  at Joomla\Database\Mysqli\MysqliDriver->disconnect()
     (/var/www/html/libraries/vendor/joomla/database/src/DatabaseDriver.php:496)
  at Joomla\Database\DatabaseDriver->__destruct()

Deprecated: Method ReflectionProperty::setAccessible() is deprecated since 8.5, as it has no effect since PHP 8.1 in /var/www/html/plugins/system/falangdriver/falangdriver.php on line 100

Deprecated: Method ReflectionProperty::setAccessible() is deprecated since 8.5, as it has no effect since PHP 8.1 in /var/www/html/plugins/system/falangdriver/falangdriver.php on line 100