T W R - S 0 8 L L / L H U S E R G U I D E
A P R I L 2 7 , 2 0 1 0
U S E R G U I D E
8
To use an external BDM cable, the user must install a header at location J400. A resistor at
R411 must also be removed to prevent contention between the external BDM cable and the
OSBDM.
To use an external BDM, the user must also apply power to the board. Power may be applied
through the OSBDM or at the COM header. Simply connecting the USB cable to the USB
connector will apply power to the board. The user may also apply power to the COM
connector at J3. Apply +3.3VDC at J3-10 and GND at J3-9. Please note that no over-voltage
or transient protection is applied at this power input.
CAUTION:
Do not apply excessive voltage at input J3-9 and J3-10. Neither over-
voltage nor transient protection is applied at this input.
CAUTION:
Do not apply power to COM connector J3 while also powering the board
through the OSBDM. Damage to the board may result.
The external BDM is now ready for use.
POWER
The TWR-S08 board may be powered from the OSBDM or from the Tower System. A
190mAH battery holder is applied for battery-powered operation. The USB current limit must
be observed while using the USB connection from the host PC to supply power to the target
board. Damage to the target board, Tower System, or host PC may otherwise occur.
POWER SELECT
Option headers V_SEL and VDD_EN select the source of input power to the target board.
When powered from the Tower System, the OSBDM voltage output is disabled.
V_SEL
The V_SEL option header allows the user to select power input either the on-board regulator
or the battery holder. The on-board regulator is supplied from the OSBDM voltage output.
Figure 2 below shows the PWR_SEL header settings.