Understanding jtag between microcontroller and devices
Every JTAG signal is unidirectional.
The JTAG controller TCK and TMS pins drives all the JTAG device TCK and TMS pins.
(and the TRST pins, if present).
Each JTAG device drives only its TDO, not any of the other JTAG lines.
In my admittedly limited JTAG experience,
I've only seen the FT2232 used as a JTAG controller, not a JTAG device.
The CPU it's connected to is the &quot;JTAG device&quot;.
a
b
c
I've never actually used 2-wire SWD (&quot;serial-wire debug&quot;), but I hear it has bidirectional lines and is sometimes is called a &quot;variant of JTAG&quot;.
I've seen microcontrollers communicate with a lot of peripherals using daisy-chain SPI, which is very similar to JTAG.
I'm not sure how RS-232 is relevant.