Difference between revisions of "J-Link OB SAM3U NordicSemi"
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+ | = VCOM functionality = |
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− | ... |
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+ | This J-Link model supports 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) |
Revision as of 17:14, 4 July 2018
VCOM functionality
This J-Link model supports 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)