Ground Contact Switch "Next steps"

innerbreed · August 14, 2010, 4:55pm

zoomkat:

When I did my testing I connected the resistor between the 5v and the I/O pin, one end of the contact switch to ground, and the other switch wire to the I/O pin. In your circuit, it looks like you may short the the board 5v directly to ground when the switch is closed. In your wiring I would connect the black wire to the I/O pin along with the resistor. This way the resistor keeps the I/O pin at 5v until the switch is closed. When the switch is closed the I/O pin is grounded and the resistor with a high value is also shorted to ground and not able to keep the I/O pin high. In your setup, I’d solder the black wire to one side of the resistor lead, and stick this lead in the I/O pin hole, and stick the other resistor lead in the 5v pin hole. Keep the yellow wire where it is.

thanks for replying. do you mean like this?:
http://i531.photobucket.com/albums/dd355/innerbreed/FSRconnection2.jpg

innerbreed · August 14, 2010, 5:05pm

yes i agree. red, black and yellow are better.
fortunately i have loads of 24awg wire. unfortunately they all go from orange, purple, green, yellow, red, and blue.

kurte · August 14, 2010, 5:16pm

Yep, totally understand about use the ones you got!

Yes your new picture look better. So when the switch is now closed, your Power will be connected to ground through the 10K resistor so not much current will flow and you can avoid the magic blue smoke

Kurt

innerbreed · August 14, 2010, 5:20pm

thumbs up. thanks guys.
i have changed all the connection now so all is ok. just need my switches.

kurt i think you should have yours before mine as iv not yet got email back. good luck and i look forward to your progress.

innerbreed · August 17, 2010, 4:46pm

here is the current code im using.
the probs i have is im not getting any response of the tars.
whats expected to happen:
The legs should be cycling though the gait then advance to the next leg once contact is made on previous leg.

The sound is beeping so i am getting a 0 reading from the sensor.

[code]
cRF_FSR con P16
cRR_FSR con P17
cLR_FSR con P18
cLF_FSR con P19

;Terain adaption sensors
cFSR sbyteTable cRR_FSR, cRF_FSR, cLR_FSR, cLF_FSR
:---------------------------------------------------
;Terrain adaption Get input from Tars pressure sensors
IF FSROn THEN
gosub ReadFSR
ELSE
RF_FSR =0
RR_FSR =0
LF_FSR =0
LR_FSR =0
ENDIF

;Balance calculations
TotalTransX = 0 'reset values used for calculation of balance
TotalTransZ = 0
TotalTransY = 0
TotalXBal = 0
TotalYBal = 0
TotalZBal = 0
IF (BalanceMode>0) THEN
for LegIndex = 0 to 2 ; balance calculations for all Right legs
gosub BalCalcOneLeg -LegPosX(LegIndex)+GaitPosX(LegIndex), |
LegPosZ(LegIndex)+GaitPosZ(LegIndex), |
(LegPosY(LegIndex)-cInitPosY(LegIndex))+GaitPosY+cFSR(LegIndex), |
LegIndex]
next

for LegIndex = 3 to 5	; balance calculations for all Left legs
  gosub BalCalcOneLeg [LegPosX(LegIndex)+GaitPosX(LegIndex), |
						LegPosZ(LegIndex)+GaitPosZ(LegIndex), |
						(LegPosY(LegIndex)-cInitPosY(LegIndex))+GaitPosY+cFSR(LegIndex), |
						LegIndex]
next
gosub BalanceBody

ENDIF

:-------------------------------------------------
ReadFSR:

input P16;AX0 P16 V-Servo / General Purpose
input P17;AX1 P17 V-Logic / General Purpose
input P18;AX2 P18 General Purpose
input P19;AX3 P19 General Purpose

IF RF_FSR=0 THEN
LegPosY(cRF)=LegPosY(cRF+1)max 60
sound p9, [50\4000]
ENDIF

IF RR_FSR=0 THEN
LegPosY(cRR)=LegPosY(cRR+1)max 60
ENDIF

IF LF_FSR=0 THEN
LegPosY(cLF)=LegPosY(cLF+1)max 60
ENDIF

IF LR_FSR=0 THEN
LegPosY(cLR)=LegPosY(cLR+1)max 60
ENDIF

IF (RF_FSR+RR_FSR+LF_FSR+LR_FSR)>=6 THEN
RF_FSR = (LegPosY(cRF)-1) min 0
RR_FSR = (LegPosY(cRR)-1) min 0
LF_FSR = (LegPosY(cLF)-1) min 0
LR_FSR = (LegPosY(cLR)-1) min 0
ENDIF

;serout s_out, i57600, [sdec RF_FSR_PosY, 13]

return[/code]

battery’s just died!!! back to morrow with this.

km6vv · August 17, 2010, 5:51pm

Is FSR a new command in basic? Otherwise I’m not seeing where the input pins are set up. Maybe not needed?

New manual on BM.

Alan KM6V

robotdude · August 17, 2010, 6:07pm

He’s using the term FSR (force sensitive resistor) for the variables, but it’s actually just ground contact switches. Maybe it stands for Find Surface Reaction. lol

robotdude · August 17, 2010, 6:13pm

The code here…

[code]ReadFSR:

input P16;AX0 P16 V-Servo / General Purpose
input P17;AX1 P17 V-Logic / General Purpose
input P18;AX2 P18 General Purpose
input P19;AX3 P19 General Purpose
[/code]

Will not read anything. That code just makes the pins inputs. Make variables to store the results in, then fill them in with the values as follows.

FLS var bit ;Front Left switch
FRS var bit ;Front Right switch
RLS var bit ;Rear Left switch
RRS var bit ;Rear Right switch
ReadFSR:
  FLS = in16
  FRS = in17
  RLS = in18
  RRS = in19

innerbreed · August 17, 2010, 7:10pm

i have defined the variables i just didnt post the obvious. sorry.

[code];[Terain adaption]
RF_FSR var bit
RR_FSR var bit
LF_FSR var bit
LR_FSR var bit

FSROn var bit[/code]

also should i change the sub

to

ReadFSR: ; Reading input from Foot Sensing Resistor #_FLS = in16 #_FRS = in17 #_RLS = in18 #_RRS = in19

km6vv · August 17, 2010, 7:15pm

Does it work now?

Alan KM6VV

innerbreed · August 17, 2010, 7:19pm

It compiles nicely…
But I will confirm any feedback tomorrow. The dreaded thing has happened… My battery’s need charging!

innerbreed · August 18, 2010, 9:15pm

Well i thought id run some test on the code. all the legs are wired and as i haven’t got my switches yet (maybe next week) i thought id just see how the code is working. i have suspended the robot from the ground for this test just so i don’t accidentally make a connection with the tars that’s not intended. anyway,

START>the bot wakes up, TRIANGLE>gets it into walk pos, CROSS>turns the sensors on
here i was expecting the legs to start dropping as the wires are not >< connected on each tar?

Anyway, now the strange things start to happen…

if i say connected any one of the tars (simulated a FSR switch) the Rear right leg moves up about an inch and then drops again. and that happens with what ever tar i connect.
also if i connect the Rear left, then the Front left drops!
but then the other strange thing is that these reactions don’t always happen, sometimes they don’t react at all.
its safe to say the connections are correct as i do get a beep command when ever a Tar is connected and Disconnected.

im kinda thinking that the original code is just running its course and not letting the tars drop and i think the TA code just needs tweaking. i hope other have better luck. i will keep trying.
Terrain_V20.rar (32.8 KB)

kurte · August 19, 2010, 4:24pm

So as I mentioned in the other thread. My parts arrived yesterday minus the three tubes I did not order. But since then I cut 3 from some 3" tubes I had from a previous version of the CHR-3 hex… So I will start to assemble them today. I am not sure I have enough wire, so may make a run to radioshack.

I am now trying to decide how I want to wire mine up. In your previous posts about how to wire it up, you are using a pull-up resistor. That is you are putting a 10K resistor between +5v and the signal pin. So when the switch is open you will have +5v going to the IO pin and when it is closed you will have 0V.

What I am thinking of doing is use a pull-down resistor. That is have the 10K resistor going between the signal pin and ground. So if I am correct when switch is open you will have 0V and when closed +5v. Does that make sense?

Also thinking about maybe trying to drill a hole in the L brackets and maybe trying to insert an LED and wire it up with the switch. Need to figure out the wiring and the like, but might be nice to see the LED go or or off when contact is made…

Kurt

robotdude · August 19, 2010, 4:38pm

A pull up pulls the signal high if it is not connected to ground. This is required because one side of the switches are tied directly to chassis ground, and this can’t change. A pull down would require a connection to 5vdc on one side of the switch to force it high when engaged.

innerbreed · August 19, 2010, 4:57pm

I connected the resistor between the 5v and the I/O pin, one end of the contact switch to ground, and the other switch wire to the I/O pin.
Then the resistor keeps the I/O pin at 5v until the switch is closed.
figure that the legs will be on the floor most of the time.
http://i531.photobucket.com/albums/dd355/innerbreed/FSRconnection2.jpg

djsfantasi · August 19, 2010, 5:14pm

Referring back to your August 14th post, it looks from that diagram that you should switch the yellow and black wires.

[PS: kurte already mentioned this change in his post, but your recent diagram didn’t seem to reflect the change. My apologies if you’ve already done so.]

The wire from the outside of the Ground Contact Switch is connected to the chassis, which is usually grounded. In this case, the black wire will always be at ground and the sensor input will also always be low. Hence the black wire should be connected to the system ground and not the microcontroller I/O pin.

The yellow wire (connected inside the ground contact switch) floats electrically when the leg is lifted. It should be connected to the microcontroller I/O pin.

If these two wires are connected in this manner, when the leg is on the ground, the yellow wire will be grounded and the signal will be low; when the leg is lifted, the yellow wire is not connected to anything and the pullup resistor makes the signal high.

innerbreed · August 19, 2010, 9:14pm

for the purpose of the picture i used black and yellow. i actually have just black and red. (i ordered more wire)

Red wire is now connected to the I/O pin along with the pull-up going to 5v.
Black wire is going to ground and is grounded to the chassis.

the connections are as shown but the colors are different.

Mine------Picture------Connection RED.......Black........I/O pin+ Resistor to 5v BLACK.....Yellow.......To Ground+ chassis
http://i531.photobucket.com/albums/dd355/innerbreed/FSRconnection2.jpg

djsfantasi · August 19, 2010, 9:35pm

But how is the red/black wire connected to the Ground Contact Switch?

Is the red wire, which is connected to the IO pin on the microcontroller board with the pull-up resistor, connected to the internal contact on the Ground Contact Foot Switch?

innerbreed · August 19, 2010, 10:25pm

http://i531.photobucket.com/albums/dd355/innerbreed/FSRconnection-1.jpg

innerbreed · August 20, 2010, 6:34pm

Been doing some work with the FSR’s and i have got the sensors work as far as i have a reaction from them when i simulate them switching.
when you start up the robot the the feet drop just below the 0 initpos position (-initpos). when the robot feel the ground they return to the 0 initpos.

so with that said, when the robot is on the ground it sits at it 0 initpos and once it makes a step and moves over a lower part of the ground the foot moves below the initpos to the -initpos.

the only problem is its either up or down and no happy medium. also once the tars feel the floor they bounce up staight away.

here is the code.

IF RR_FSR=0 THEN LegPosY(cRR)=-LegPosY(cRR+1)max 100 ; sound p9, [50\4000] elseif RR_FSR=1 LegPosY(cRR)=0 else RR_FSR = (-LegPosY(cRR)-1) min 0 ENDIF

so i have tried adding a command to save the state of the leg but its not working for me. here is what i was thinking.

[code] ;If foot up
IF RF_FSR=0 THEN ;Lower legs
LegPosY(cRF)=-LegPosY(cRF+1)max 100
; sound p9, [50\4000]
elseif (RF_FSR=0) ;if foot up
LegPosY(cRF) = cInitPosY(cRF)+cFSR

	;Store current status
	prev_RF_FSR = RF_FSR	         
       
  ELSE ;Return prev leg back to the init position
    LegPosY(prev_RF_FSR) = cInitPosY(prev_RF_FSR)

  ENDIF[/code]

with this im just getting the same response.!

any tips on how this should be written.
id like the tars to drop slowly to the floor when they detect they have been elevated, then they stay at their position once the floor has been found. once the leg lifts, the tars need to return to their initpos again.