Difference between revisions of "J-Link OB"

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(Created page with "__TOC__ =J-Link OB SAM3U NordicSemi= =J-Link-OB SAM3U= =J-Link-OB-RX621-ARM-SWD=")
 
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=J-Link OB SAM3U NordicSemi=
 
=J-Link OB SAM3U NordicSemi=
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__TOC__
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== VCOM functionality ==
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This J-Link model supports VCOM.
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=== Supported baudrates ===
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This J-Link OB supports max. 1 MBaud. The internal divider is calculated as follows:
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Baudrate = 96000000 / Div * 16;
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Div = 96000000 / (Baudrate * 16);
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'''Note:''' The real baudrate and the selected one should not deviate more than 3% to guarantee proper communication on VCOM.
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=== Pin driving policy ===
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The following pins are available on this OB:
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* OB_Tx (driven by J-Link OB)
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* OB_Rx (driven by target)
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* CTS (driven by target. LOW == Target ready to receive data)
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* RTS (driven by J-Link OB. LOW == J-Link OB ready to receive data)
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J-Link OB starts driving its VCOM output pins as soon as it receives a "set baudrate" command. This command is send by the PC as soon as a COM port is opened. Unfortunately, there is no specific command / packet etc. send by the PC in case a COM port is opened. Therefore the "set baudrate" approach is the only one to detect COM port activity.
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J-Link OB stops driving the RTS pin if J-Link OB detects that hardware flow control is not used on the target side.
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=== Hardware flow control support ===
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Hardware flow control is supported by this J-Link OB. By default, J-Link detects at runtime if the target uses flow control or not.
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This is done as follows:
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* If CTS is detected as HIGH (Target not ready) before the first character is sent by J-Link OB, the pin is assumed to be not used by the target and flow control on the J-Link side gets disabled (CTS is ignored from now on, J-Link stops driving RTS)
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==== Force or disable hardware flow control ====
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It is possible to configure J-Link OB to bypass the hardware flow control auto-detection in the firmware and assume that hardware flow control is always or never used. This can be done via J-Link Commander and the following command:
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SetHWFC Enable/Disable/Force
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'''Note:''' This setting gets active immediately and survives a power-cycle of J-Link.
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* '''Enable:''' Default. Enables hardware flow control and runtime auto-detection
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* '''Disable:''' Disables hardware flow control (never used)
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* '''Force:''' Enables hardware flow control and bypasses runtime auto-detection (RTS is kept driven and CTS is kept sampling)
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[[File:OB_SAM3U_NordicSemi_SetHWFC.png|Force hardware flow control|thumb|none]]
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===== Minimum requirements =====
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* J-Link software V6.33h (beta) or later ([https://www.segger.com/downloads/jlink/#J-LinkSoftwareAndDocumentationPackBeta Download latest beta])
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* J-Link software V6.34 (release) or later ([https://www.segger.com/downloads/jlink/#J-LinkSoftwareAndDocumentationPack Download latest release])
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* J-Link OB SAM3U NordicSemi running firmware from V6.33h or later
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=J-Link-OB SAM3U=
 
=J-Link-OB SAM3U=
 
=J-Link-OB-RX621-ARM-SWD=
 
=J-Link-OB-RX621-ARM-SWD=

Revision as of 09:17, 26 March 2019

J-Link OB SAM3U NordicSemi

VCOM functionality

This J-Link model supports VCOM.

Supported baudrates

This J-Link OB supports max. 1 MBaud. The internal divider is calculated as follows:

 Baudrate = 96000000 / Div * 16;
 Div = 96000000 / (Baudrate * 16);

Note: The real baudrate and the selected one should not deviate more than 3% to guarantee proper communication on VCOM.

Pin driving policy

The following pins are available on this OB:

  • OB_Tx (driven by J-Link OB)
  • OB_Rx (driven by target)
  • CTS (driven by target. LOW == Target ready to receive data)
  • RTS (driven by J-Link OB. LOW == J-Link OB ready to receive data)

J-Link OB starts driving its VCOM output pins as soon as it receives a "set baudrate" command. This command is send by the PC as soon as a COM port is opened. Unfortunately, there is no specific command / packet etc. send by the PC in case a COM port is opened. Therefore the "set baudrate" approach is the only one to detect COM port activity.

J-Link OB stops driving the RTS pin if J-Link OB detects that hardware flow control is not used on the target side.

Hardware flow control support

Hardware flow control is supported by this J-Link OB. By default, J-Link detects at runtime if the target uses flow control or not. This is done as follows:

  • If CTS is detected as HIGH (Target not ready) before the first character is sent by J-Link OB, the pin is assumed to be not used by the target and flow control on the J-Link side gets disabled (CTS is ignored from now on, J-Link stops driving RTS)

Force or disable hardware flow control

It is possible to configure J-Link OB to bypass the hardware flow control auto-detection in the firmware and assume that hardware flow control is always or never used. This can be done via J-Link Commander and the following command:

 SetHWFC Enable/Disable/Force

Note: This setting gets active immediately and survives a power-cycle of J-Link.

  • Enable: Default. Enables hardware flow control and runtime auto-detection
  • Disable: Disables hardware flow control (never used)
  • Force: Enables hardware flow control and bypasses runtime auto-detection (RTS is kept driven and CTS is kept sampling)
Force hardware flow control
Minimum requirements

J-Link-OB SAM3U

J-Link-OB-RX621-ARM-SWD