5 Output Up Down Switch (gear selector)

[Phat]

Hi guys,

I did a search, but I didnt come up with much so ill post away.

In my car I have a automatic transmission, which has been manualised, there is a series of relays that correspond to each fwd gear.
I want to controll these with a simple "up" "down" button mounted on the steering wheel, also, I want a brake sw input that will drop the car out of OverDrive on brake pedal depress should the car be in that gear.
here is a basic Paint Drawing lol



i feel that it shouldnt be TOO tricky, so if someone could point me in the right direction, or even suggest a circuit that I could use/modify to suit my needs, it'd be awsome.

 

[3v0]

I would use a state machine. You can build it with hardware logic chips or a uC and software.

The starting state is NEUTRAL.
If UP move to state 1st.
If DOWN do nothing.

State 1st
If UP move to state 2nd
IF DOWN move to state NEUTRAL

State 2nd
IF UP move to state 3rd
If DOWN move to state 1st

State 3rd
IF UP move to state 4th
If DOWN move to state 2nd

State 4th
IF UP move to state OD
If DOWN move to state 3rd

State OVERDRIVE
If UP do nothing
IF DOWN move to state 4th
IF BRAKE move to state 4th

When in a state the coresponding relay is closed.

Hi guys,

I did a search, but I didnt come up with much so ill post away.

In my car I have a automatic transmission, which has been manualised, there is a series of relays that correspond to each fwd gear.
I want to controll these with a simple "up" "down" button mounted on the steering wheel, also, I want a brake sw input that will drop the car out of OverDrive on brake pedal depress should the car be in that gear.
here is a basic Paint Drawing lol

View attachment 18687

i feel that it shouldnt be TOO tricky, so if someone could point me in the right direction, or even suggest a circuit that I could use/modify to suit my needs, it'd be awsome.

 

[crutschow]

The simplest approach I can think of, not using a uC, is to use an Up/Down counter such as a CD40192 or CD40193 connected to a binary to decimal converter such as a CD4028.

The 40193 has two clock inputs. The ClOCK UP input counts up (connect to the shift-up switch) and the CLOCK DOWN counts down (connect to the shift-down switch).

The CD4028 converts the binary from the counter to one of 9 outputs (only 6 are used here for the 5 shift positions and neutral).

Some additional logic is required to insure that the logic powers up in the 0 (neutral) state; to limit the count between 0 through 5; to insure that a down switch doesn't roll over the counter from 0 to 5; and to insure that the brake reduces the count to 4 only when in the count 5 (OD) position.

The switches will need debounce circuits so you shift only one gear per button push.

Buffer amps are also needed to drive the relays.