The ISOARM is a straightforward, easy-to-use product. Just connect your emulator (debug probe) to one of the three emulator JTAG connections and then connect your target board's JTAG connection to one of the target side connectors. The ISOARM is unique from most other isolation adapters by providing three common ARM JTAG connections on both the emulator and target sides allowing the adapter to be also used as a converter.
The ISOARM does expect the target board to provide between 20-80 mA of 1.8, 3.3 or 5.0 volts on JTAG pin 1 (VCC) to power the adapter's target side components. The emulator side is also powered by the target, which is why you may need up to 80 mA when using 1.8V IOs (less for 3.3V or 5.0V). If the target cannot provide enough current to power the emulator side, don't worry, you can switch off power to the emulator side bringing the current down to 20-25 mA and use one of the other power options (power from emulator or USB cable).
There are two green LEDs on the ISOARM that indicate when there is power applied to the target and emulator sides of the adapter. The red LED is used for the nRESET JTAG signal and illuminates when that signal is active (low).
Two switches are provided that enable support of both standard JTAG and SWD protocols. Just make sure that the switches are in the same position, JTAG or SWD, to match your desired protocol.
- Supports I/O voltages of 1.8/3.3/5.0 volt targets
- Serial wire debug (SWD) and IEEE 1149.1 (JTAG) protocols supported
- High electromagnetic immunity
- High Speed operation: up to 24MHz TCK
- Connections: ARM Std 20-pin, ARM Cortex 10 & 20-pin
- Voltage Isolation: 5K Vrms
- Powered by USB, Target VCC or Emulator
- Current consumption is 20-80mA (varies with I/O voltage level and SW3 setting)
- RoHS Compliant
JTAG Connector Signal Definitions [SWD Signals]
(J1 & J2)
(J6 & J7)
(J3 & J4)
1 VCC * VCC * VCC * 2 VCC * TMS [SWDIO] TMS [SWDIO] 3 nTRST GND GND 4 GND TCK [SWDCLK] TCK [SWDCLK] 5 TDI [NC] GND GND 6 GND TDO [SWO] TDO [SWO] 7 TMS [SWDIO] KEY KEY 8 GND TDI [NC] TDI [NC] 9 TCK [SWDCLK] GND GND 10 GND nRESET nRESET 11 RTCK GND/PWR ** 12 GND GND 13 TDO [SWO] GND/PWR ** 14 GND GND 15 nRESET GND 16 GND GND 17 NC GND 18 GND GND 19 GND/PWR ** GND 20 GND GND * VCC J2, J4 & J6: The VCC signal pins on the target side supply power for isolator IC logic, LEDs and emulator side. SW3 can be used to turn off power to emulator side if necessary to reduce power draw from the target. J1, J3 & J7: The VCC signal pins on the emulator side are fixed at 3.3V. ** PWR J7 Pins 11 & 13: These pins are used as power input from the emulator (i.e I-JET). J1 Pin 19: This pin is used as power input from the emulator (i.e. JLINK). On the target side connectors (J2 & J6), these are ground pins.