Test bidi_bridge direction changes and automatic bridging

Va a 0 pulse 0 3 0 1u 1.2u 500u 1m
Vb b 0 pulse 0 3 0 1u 1.2u 100u 200u
Vctl ctl 0 pulse 0 3 10m 1u 1u 10m 20m

Ainv ctl not_ctl invert
.model invert d_inverter

* Transmitter/receiver for an analogue bus line

.subckt driver in enable out bus
Atran in enable int tristate
Arec int out buffer
Rout int bus 20 // Make bus an analogue node, with bridge
.ends

.model buffer d_buffer
.model tristate d_tristate

Xa a ctl out_a bus driver
Xb b not_ctl out_b bus driver
Rload bus 0 1k

.control
save  a out_a b out_b
tran 1m 40m
plot out_a
listing e
.endc
.end