For people having experience with JLINK Lite ARM (or JLINK Lite CortexM) programmers for non-3.3V targets, here are some questions:
- The JLINK spec mentiones VIF to be a fixed 3.3V for the JLINK Lite programmers. Does this mean that the programmer would not work unless VTref pin voltage is 3.3V?
- If the JLINK Lite programmer supports VTref 2.4V, would the interface circuit below work?
- As I understand it, the JLINK LITE programmer has a fixed interface voltage of 3.3V, meaning SWCLK would be driven at 3.3V levels. To reduce current sinking in to the 2.4V supply via SWD_CLK pin of the MCU, I will use a current limiting resistor (R3). SWD_DATA and nRESET pins of the MCU would anyways have pull ups to 2.4V, so those should be OK. Does this makes sense?
– Schematic created using CircuitLab