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Note:
The target device should draw less than 100 mA of current using a USB port that can supply at least 250 mA
of power (including the power usage of the USB-SWD programming board and target device). Going beyond
this limit may cause damage to the target module/device, USB-SWD programming board, or PC.
When programming BT510 modules, this setup must be used. The voltage should be set to 3.3v to closely match the coin cell
which operates at 3v (the battery cannot be connected whilst the debugger is connected, therefore there is no issue of a
voltage mismatch or back-powering of the coin cell).
To use the target’s voltage source as a reference voltage, set the SW6 switch to the
Supply in
position and set the SW5 switch
into the 1V8 position. The reference voltage of the target must be supplied on pin 1 of the ARM-debug connector (P1) or pin 1
of the BT510 IDC connector (J3) with a suitable ground connection to the ground of the USB-SWD programmer board.
The USB-SWD programmer board operates at the voltage set on SW5 until the voltage of an external device is sensed. We
recommend that you keep this switch on 1.8v if devices operating at less than 3.3v are connected. This prevents any power
passing from the USB-SWD programmer board to the target device before the USB-
SWD programmer board’s reference
voltage circuitry has updated with the voltage being synchronised to all power-systems on the board.
The USB-SWD programmer has various volatile and non-volatile options that can be set by copying empty files with specific
filenames to the USB mass storage device. There is additional information about this feature on the MBED DAPLINK github
site:
https://github.com/ARMmbed/DAPLink/blob/master/docs/MSD_COMMANDS.md
displays the supported actions (volatile, these are reset to defaults when the USB-SWD programmer is powered up)
for the USB-SWD programmer.
Table 1: Supported actions
Filename
Function
Checking
start_bl.act
Enters bootloader mode on the USB-SWD
programmer so that the firmware can be
upgraded
If the red LED and green LED are on constantly (and the
mass storage USB drive is named LC_SWDMAINT) then
the device is in bootloader mode.
start_if.act
Enters normal mode on the USB-SWD
programmer (if device is in bootloader mode
and BOOTLOADER header pin is not fitted)
If the red LED and green LED are both off or just one is
on (and the mass storage USB drive is not named
LC_SWDMAINT) then the device is in normal mode.
refresh.act
Closes the USB mass storage device and
re-opens it