About the StingRay...

Ramboman

I was so happy to get a StingRay with the Ping kit for X-mas. My project is to develop a remote controlled robot with X-Bee's. I have some practice with the Propeller and before with the SumoBot...
I made only one modification : I replaced the old fashioned NiMh cells with a 2s LiFe pack... no problem...
Several days later, today... I connect the StingRay to my PC to start programming... no current...
Check with the multimeter : pack at 0.7V... so low that the even my charger refuse to charge it... I had to get around with my lab power supply...
What happend ? The switch was on OFF !
Funny design... the switch DOES NOT cut power... the pack discharged on God knows what.
Fortunately, LiFe are strong enough, they will recover...
Next modifications : a MAIN switch... recommended to all users

erco

Nice to hear you like your Stingray! The main board uses a 3-position switch. There is an all-off position at one end, which completely disconnects the battery. The center position is "electronics on, motor off" (useful for bench testing) and the other end is "electronics and motor on".

Are you certain you didn't leave it in the middle position, which would still drain your batteries eventually? Always make sure the LEDs near the barrel jack are off.

Roy Eltham

This is a known issue. Even in the "all off position" the WIN still goes to the H-Bridge and the VIN connections on the board. You have to disconnect the battery completely to keep it from being slowly drained.
Ken has already posted a reply to another thread with a list of known issues that are going to be addressed soon (this is one of them).

RobotWorkshop

The thread that Roy mentions is located here:

http://forums.parallax.com/showthread.php?127511-Stingray-Plans-question-for-Ken

It is worth reading!

Robert

Whit

I second reading Ken's update on the Stingray thread. erco is right (and you were too) - the general assumption is that off is off. Though not in this case!

I would add that even with the addition of a master off switch - I alway disconntect or remove the battery after use.

erco

I DID assume! And you know what that leads to...

Ramboman

Going (slowly) further...
Loading "ping" program... no reaction...
Loading "motor test" program... no reaction...
Loading "led test" program, with those funny transistors (never used them before... translators ?)
Strictly following instructions... searching transistor connection on web... it works ;-)
At least board is not dead on arrival...
Loading "motor test" again AND moving switch a lot... now it works... bad contact ?
Testing both motors... OK
Reloading "ping" program... nothing... why ?
Now trying to understand "ping" program... very confuse...
PWMx8 ???
Will rewrite it my way...
Or drop the whole bord and use a simple USB propeller and a motor driver...
That board introduces useless complexity...
Why make it simple if we can make it complex ?

Ramboman

Going further...
Rewrote the "mvsr" move stingray...

'My StingRay v0

CON
_clkmode = xtal1 + pll16x
_clkfreq = 80_000_000

sp = 127

OBJ
pw : "pwmx8"

VAR

PUB main | lp, rp 'left & right pulse
'initialize
pw.start(24, %00001111, 23_000) 'start pwmx8 for 24..27 @ 23kHz

'main loop
mvsr(sp, sp)
waitcnt(clkfreq + cnt) 'forward for 1 sec
mvsr(0, 0)
waitcnt(clkfreq + cnt) 'wait for 1 sec
mvsr(-sp, -sp)
waitcnt(clkfreq + cnt) 'backward for 1 sec
mvsr(0, 0)
repeat

PUB mvsr(lw, rw) 'set left & right wheel from -255 to +255, 0 = stop
lw := -255 #> lw <# 255
rw := -255 #> rw <# 255

ifnot lw & $80_00_00_00
pw.duty(24, 0)
pw.duty(25, lw & $ff) 'left forward
else
pw.duty(25, 0)
pw.duty(24, (0-lw) & $ff) 'left backward

ifnot rw & $80_00_00_00
pw.duty(27, 0)
pw.duty(26, rw & $ff) 'right forward
else
pw.duty(26, 0)
pw.duty(27, (0-rw) & $ff) 'right backward

Loading... FLOP...
Moving switch a lot... OK...
Probably bad quality switch...

Will go further with compass...