Engine Management

clean up is done... time for fun.

Sharp eyed folks out there might recognize, that most all the parts are in place for performing ignition management. The tach event array tkEv[] holds the TDC for each cylinder. By subtracting a value for total advance from each of the TDCs a coil event (coEv[]) angle is obtained. This is done simply in a short loop in the 1mS ignition process while the engine is running, similar to the loop to set the tkEv[] values during engine off. The value of total advance is calculated once, then applied to the tkEv in the loop. The other part of the operation is the start of dwell for each event, the dwell is a value that provides sufficient time to charge the coil, but not too much beyond fully charging the coil. This value is also captured as an angle, and the start of event (cost[]) is calculated by subtracting the dwell angle from the coil event angle. This is also done in the loop. The calculation of dwell angle is also a one time operation, and then applied in the loop.

That wordy explanation, works out to just a few lines of code.

UWord coEv[8];
UWord coSt[8];

void rtUpdateIgn(void) {
...
    updateTotAdv();
    updateDwlAng();
...
    if (tmOut > 0) {
...
        for (c = 0; c < cylCt; c++) {
            coEv[c] = tkEv[c] - getTotAdv();
            coSt[c] = coEv[c] - getDwlAng();
        }
...

The two functions getTotAdv() and getDwlAng() return the angle of advance, and the angle of dwell calculated the one time.

The last part is to include the operation in the scheduler, in the same way as the tach. The difference being, coil operation passes the cylinder number for cases where the operation is coil on plug, so the call to setCoil() has the coil number as well as the state.

            if ((min < coSt[c]) && (coSt[c] <= max)) { ft = (SLong)(coSt[c] - pa) * bs / PART2; ignCoHi(c, ft, tm); }
            if ((min < coEv[c]) && (coEv[c] <= max)) { ft = (SLong)(coEv[c] - pa) * bs / PART2; ignCoLo(c, ft, tm); }

and the same for the other range of min/max

            if ((min < coSt[c]) || (coSt[c] <= max)) { ft = (SLong)(coSt[c] - pa) * bs / PART2; ignCoHi(c, ft, tm); }
            if ((min < coEv[c]) || (coEv[c] <= max)) { ft = (SLong)(coEv[c] - pa) * bs / PART2; ignCoLo(c, ft, tm); }

The coil process takes over the fast timer operation, and the tach is moved to the slow operation.

You might ask what values should go in total advance and dwell angle, and you are right to ask. For now, something like 20 degrees (1820) for dwell and 8 degrees (728) for dwell should be fine. To run some preliminary testing, the routines updateTotAdv() and updateDwlAng() can be stubbed out, and the getTotAdv() and getDwlAng() just return the constant values.

Now it's getting fun.

Jack

clean up is done... time for fun.

Sharp eyed folks out there might recognize, that most all the parts are in place for performing ignition management. The tach event array tkEv[] holds the TDC for each cylinder. By subtracting a value for total advance from each of the TDCs a coil event (coEv[]) angle is obtained. This is done simply in a short loop in the 1mS ignition process while the engine is running, similar to the loop to set the tkEv[] values during engine off. The value of total advance is calculated once, then applied to the tkEv in the loop. The other part of the operation is the start of dwell for each event, the dwell is a value that provides sufficient time to charge the coil, but not too much beyond fully charging the coil. This value is also captured as an angle, and the start of event (cost[]) is calculated by subtracting the dwell angle from the coil event angle. This is also done in the loop. The calculation of dwell angle is also a one time operation, and then applied in the loop.

That wordy explanation, works out to just a few lines of code.

UWord coEv[8];
UWord coSt[8];

void rtUpdateIgn(void) {
...
    updateTotAdv();
    updateDwlAng();
...
    if (tmOut > 0) {
...
        for (c = 0; c < cylCt; c++) {
            coEv[c] = tkEv[c] - getTotAdv();
            coSt[c] = coEv[c] - getDwlAng();
        }
...

The two functions getTotAdv() and getDwlAng() return the angle of advance, and the angle of dwell calculated the one time.

The last part is to include the operation in the scheduler, in the same way as the tach. The difference being, coil operation passes the cylinder number for cases where the operation is coil on plug, so the call to setCoil() has the coil number as well as the state.

            if ((min < coSt[c]) && (coSt[c] <= max)) { ft = (SLong)(coSt[c] - pa) * bs / PART2; ignCoHi(c, ft, tm); }
            if ((min < coEv[c]) && (coEv[c] <= max)) { ft = (SLong)(coEv[c] - pa) * bs / PART2; ignCoLo(c, ft, tm); }

and the same for the other range of min/max

            if ((min < coSt[c]) || (coSt[c] <= max)) { ft = (SLong)(coSt[c] - pa) * bs / PART2; ignCoHi(c, ft, tm); }
            if ((min < coEv[c]) || (coEv[c] <= max)) { ft = (SLong)(coEv[c] - pa) * bs / PART2; ignCoLo(c, ft, tm); }

The coil process takes over the fast timer operation, and the tach is moved to the slow operation.

You might ask what values should go in total advance and dwell angle, and you are right to ask. For now, something like 20 degrees (1820) for dwell and 8 degrees (728) for dwell should be fine. To run some preliminary testing, the routines updateTotAdv() and updateDwlAng() can be stubbed out, and the getTotAdv() and getDwlAng() just return the constant values.

Now it's getting fun.

Jack