Customize ARM20 JTAG interface for use on microcontrollers. Can provide 5V, 3.3V, 1.8V, or 1.2V on VTRef to power the target. VTRef is pin 1 of the JTAG conector. Can also provide a 12V programming voltage and switch to an SWD mode as discussed here https://github.com/arduino/OpenOCD/blob/master/tcl/interface/ftdi/swd-resistor-hack.cfg

Note that to supply VTRef, the board requires a 5V input. This can be via USB, a 2 pin header (J1), pin 2 of the host side JTAG connector, or pin 19 of the host side JTAG connector. Pin 2 is documented to be NC, but on some adapters provides voltage to the target. Pin 19 is documented as DBGACK, but is sometimes used to provide 5V to the target.

The 12V programming voltage can optionally be supplied on the target nTRST (pin 3). If this is configured, 12V is supplied with the host side nTRST pin is low. As with VTRef, a 5V input is required.

• J1 - Access to 5V (input or output)
• J2 - Low Voltage (LV) Setting - 3.3V, 1.8V or 1.2V if NC
• J3 - 5V source - Pin 2 of host or Pin 19 of host (or NC)
• J5 - VTRef source - LV or 5V (or NC for target supplied)
• J6 - JTAG or SWD mode (TDO and TDI (via 470ohm resistor) from programmer tied to target TMS)
• J7 - nTRST output - nTRST input (PASS) or 12V (active when nTRST is low)
• J8 - Pin 2 target - Pin 2 host (PASS) or VTRef
• J9 - Pin 19 target - Pin 19 host (PASS) or VTRef

refdes:value:footprint:partno:rating:tolerance:DNP:qty
J4:unknown:HEADER_STRADDLE_20:S9197-ND:unknown:unknown:unknown:1
P2:unknown:HEADER_STRADDLE_20:S9172-ND:unknown:unknown:unknown:1
R4:470:0402:unknown:unknown:unknown:unknown:1
U1:unknown:sot23-5:LM3671MF-ADJ/NOPBTR-ND:unknown:unknown:unknown:1
L1:2.2uH:0806:587-2606-1-ND:unknown:unknown:unknown:1
C2:10u:0402:unknown:6.3V:unknown:unknown:1
C1:4.7u:0402:unknown:6.3V:unknown:unknown:1
U3:unknown:sot23-5:AP3012KTR-G1DITR-ND:unknown:unknown:unknown:1
C5:1u:0402:unknown:16V:unknown:unknown:1
R5:13k:0402:unknown:unknown:unknown:unknown:1
R7:1.5k:0402:unknown:unknown:unknown:unknown:1
L2:10u:0806:587-2452-2-ND:unknown:unknown:unknown:1
D1:unknown:0805p:478-7800-2-ND:unknown:unknown:unknown:1
Q1:IRF9520N:sot23-gsd:DMP3098LQ-7DITR-ND:unknown:unknown:unknown:1
R1,R2,R3:10k:0402:unknown:unknown:unknown:unknown:3
U2:unknown:sot23-5:296-8485-2-ND:unknown:unknown:unknown:1
P1:unknown:10118194-0001lf:609-4618-1-ND:unknown:unknown:unknown:1
J1:unknown:HEADER_2x1:unknown:unknown:unknown:unknown:1
J6:unknown:HEADER_2x3:unknown:unknown:unknown:unknown:1
C4:1u:0402:unknown:6.3V:unknown:unknown:1
J2,J3,J5,J7,J8,J9:unknown:HEADER_3x1:unknown:unknown:unknown:unknown:6
C3:0.1u:0402:unknown:6.3V:unknown:unknown:1
C7:68p:0402:unknown:6.3V:unknown:unknown:1
C6:12p:0402:unknown:6.3V:unknown:unknown:1
R9:200k:0402:unknown:unknown:unknown:unknown:1
R8:280k:0402:unknown:unknown:unknown:unknown:1
R10:232k:0402:unknown:unknown:unknown:unknown:1
R11:66.5k:0402:unknown:unknown:unknown:unknown:1