[Dprglist] Arduino Code Troubles
John Gauthier
zizumara at sbcglobal.net
Fri Dec 17 13:28:51 PST 2021
As a side note, I believe there is great value in defensive programming
as a habit. In my code, I always use macros to define constants,
especially when using them as indicies of an array representing a
message. In this case, you could use
#define US_LEFT 0
#define US_MID 1
#define US_RIGHT 2
#define IR_LEFT 3
#define IR_RIGHT 4
#define TIME_DIFF 5
#define BUFF_SIZE 8
#define SONAR_NUM 3
#define IR_NUM 2
#define MAX_DISTANCE 200
#define DIST_UNKNOWN 999
assert(SONAR_NUM + IR_NUM <= BUFF_SIZE);
uint32_t cm[BUFF_SIZE];
for (i = 0; i < BUFF_SIZE; ++i) {
cm[i] = 0;
}
irSensorL.read();
cm[IR_LEFT] = irSensorL.ranging_data.range_mm / 10;
if (cm[IR_LEFT] > MAX_DISTANCE) {
cm[IR_LEFT] = DIST_UNKNOWN;
}
Coding constants with macros makes it hard to make mistakes, especially
when making modifications to the code. It also makes reading
the code much easier. This was a C coding standard at two companies
where I have worked.
John G.
> uint16_t maxDistance = 200; // Also used with NewPing.h library
> .
> . // Other code here
> .
> irSensorL.read(); // Read IR sensor... This is working!
> cm[3] = irSensorL.ranging_data.range_mm/10; // This returns 268
> if (cm[3] > maxDistance) {
> cm[3] = 999; /
> }
> Serial.println(cm[3]); / cm[3] value is always = 999
> sendData();
On 12/17/2021 10:13 AM, Pat Caron via DPRGlist wrote:
>
> What I meant to say last night is the array size is cm[8]. The values
> for SONAR_NUM == 3 and IR_NUM == 2
> This should not be overrunning the array as it only loops through 5 times.
> I have tried setting maxDistance as uint32_t without any difference.
> I have commented out the sendData() function and added some
> Serial.print statements prior to reassigning the values. (shown in output)
>
> #define SONAR_NUM 3
> #define IR_NUM 2
> uint32_t cm[8] = {0,0,0,0,0,0,0,0}; // Create array
> uint16_t maxDistance = 200; // Also used with NewPing.h libraray
> char *position[] = {"us_Left", "us_Mid", "us_Right", "ir_Left",
> "ir_Right", "cm[5]", "cm[6]", "cm[7]"};
> .
> . // Other code here
> .
>
> void oneSensorCycle() { // Sensor ping cycle complete, do something
> with the results.
> for (uint8_t x = 0; x < (SONAR_NUM + IR_NUM); x++) {
> Serial.print("cm[");
> Serial.print(x);
> Serial.print("] = ");
> Serial.println(cm[x]);
> if ((cm[x] == 0) or (cm[x] > maxDistance)) {
> cm[x] = 999;
> }
> }
> if (troubleshoot) {
> for (uint8_t i = 0; i < (SONAR_NUM + IR_NUM); i++) {
> Serial.print("| ");
> Serial.print(position[i]);
> Serial.print(" = ");
> Serial.print(cm[i]);
> Serial.print("cm ");
> }
> Serial.print("| ");
> Serial.print("Time = ");
> Serial.print(elapsedMillis);
> Serial.print("mS");
> Serial.println();
> }
> //else {
> // sendData();
> //}
> }
>
>
> Loop() {
> .// other code
> oneSensorCycle()
> . // more code
> }
>
> Serial output:
>
> -- Miniterm on /dev/ttyUSB-sensors 115200,8,N,1 ---
> --- Quit: Ctrl+C | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
> cm[0] = 0
> cm[1] = 95
> cm[2] = 91
> cm[3] = 85
> cm[4] = 246
> | us_Left = 999cm | us_Mid = 999cm | us_Right = 999cm | ir_Left =
> 999cm | ir_Right = 999cm | Time = 44mS
>
> ...Pat C
>
>
> On Fri, Dec 17, 2021 at 10:07 AM Chris Netter <netterchris at gmail.com>
> wrote:
>
> The for loop stops at x < 8, so it won’t overrun.
>
> What if you remove the sendData() call? Does that help?
>
> Also, make sure you have declared any global variables which are
> modified by interrupts or other tasks as “volatile”, otherwise the
> compile may decide to optimize away parts of your code.
>
> Chris
>
> *From: *Doug Paradis <mailto:paradug at gmail.com>
> *Sent: *Thursday, December 16, 2021 11:46 PM
> *To: *Chris Netter <mailto:netterchris at gmail.com>
> *Cc: *Pat Caron <mailto:patcaron at mail.com>; dprglist at lists.dprg.org
> *Subject: *Re: [Dprglist] Arduino Code Troubles
>
> Pat,
>
> for (uint8_t x = 0; x < (SONAR_NUM + IR_NUM); x++) {
>
> If SONAR_NUM _ IR_NUM = 8 then you are overrunning the array
> which goes 0 to 7.
>
> Regards,
>
> Doug P.
>
> On Thu, Dec 16, 2021 at 8:53 PM Chris Netter via DPRGlist
> <dprglist at lists.dprg.org> wrote:
>
> So Markus and Karim already pointed out that the original code
> snipped works as designed.
>
> It’s also been pointed out already that you are mixing data
> types. I don’t think that’s the issue, but worth trying to
> make both the array and maxDistance uint16_t
>
> As for this new code snippet:
>
> I don’t see any obvious issue with the for loop. Are you
> positive that SONAR_NUM + IR_NUM == 8 ? if not, you are
> overshooting the array and that can cause all kinds of
> non-obvious issues.
>
> Also, what does sendData() do? Could it have some
> side-effects? Maybe its causing a stack overflow, array
> bounds overflow, or similar, which in turn causes non-obvious
> issues?
>
> *From: *Pat Caron via DPRGlist <mailto:dprglist at lists.dprg.org>
> *Sent: *Thursday, December 16, 2021 9:04 PM
> *To: *dprglist at lists.dprg.org
> *Subject: *Re: [Dprglist] Arduino Code Troubles
>
> Hi guys, here is a better example to show what is happening
> taken from actual code:
>
> .... other code
> for (uint8_t x = 0; x < (SONAR_NUM + IR_NUM); x++) { //
> SONAR_NUM + IR_NUM = 8
> if ((cm[x] == 0) || (cm[x] > maxDistance)) {
> cm[x] = 999;
> }
>
> sendData();
>
> }
>
> Printed values cm[0] to cm[5] (us_Left to ir_Right) without
> the above if statement
> | us_Left = 0cm | us_Mid = 95cm | us_Right = 51cm | ir_Left =
> 84cm | ir_Right = 252cm | Time = 45mS
>
> Printed values cm[0] to cm[5] with the above if statement
> \| us_Left = 999cm | us_Mid = 999cm | us_Right = 999cm |
> ir_Left = 999cm | ir_Right = 999cm | Time = 44mS
>
> ...Pat C
>
> On Thu, Dec 16, 2021 at 8:45 PM Karim Virani
> <pondersome64 at gmail.com> wrote:
>
> It's doing what it's coded to do
>
> On Thu, Dec 16, 2021 at 7:42 PM Pat Caron via DPRGlist
> <dprglist at lists.dprg.org> wrote:
>
> Hi Murray, I did try that with the same results.
> NewPing.h library is looking for a uint16_t although
> it didn't complain when I tried that.
>
> ...Pat C
>
> On Thu, Dec 16, 2021 at 8:35 PM Murray Altheim via
> DPRGlist <dprglist at lists.dprg.org> wrote:
>
> Hi Pat,
>
> What if you define maxDistance as uint32_t?
>
> Cheers,
>
> Murray
>
> On 17/12/21 2:27 pm, Pat Caron via DPRGlist wrote:
> > Hi guys, I'm looking for help with the following
> Arduino code.
> >
> > uint32_t cm[8] = {0,0,0,0,0,0,0,0}; //
> Create array
> > uint16_t maxDistance = 200; // Also used
> with NewPing.h library
> > .
> > . // Other code here
> > .
> > irSensorL.read(); // Read IR sensor... This
> is working!
> > cm[3] = irSensorL.ranging_data.range_mm/10;
> // This returns 268
> > if (cm[3] > maxDistance) {
> > cm[3] = 999; /
> > }
> > Serial.println(cm[3]); / cm[3] value is
> always = 999
> > sendData();
> >
> > The cm[3] value is always 999 when I run this.
> > If I comment out the if cm[3]... statement cm[3]
> value is then 268.
> >
> > ...Pat C
> >
> > _______________________________________________
> > DPRGlist mailing list
> > DPRGlist at lists.dprg.org
> > http://lists.dprg.org/listinfo.cgi/dprglist-dprg.org
> >
>
> --
>
> ........................................................................
> Murray Altheim <murray18 at altheim dot com>
> = = ===
> http://www.altheim.com/murray/ === ===
> = = ===
> In the evening
> The rice leaves in the garden
> Rustle in the autumn wind
> That blows through my reed hut.
> -- Minamoto no Tsunenobu
>
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