[Dprglist] Arduino Code Troubles
Doug Paradis
paradug at gmail.com
Fri Dec 17 14:18:23 PST 2021
+1 on Rud defensive approach.
On Fri, Dec 17, 2021 at 4:07 PM Rud Merriam via DPRGlist <
dprglist at lists.dprg.org> wrote:
> Since you opened the door (LOL).
>
> Ardino code is C++ so as a C++ pedant I'll suggest a different defensive
> approach... Macros are problematic. I think C allows the following.
>
> enum Positions { // might do enum struct Positions : uint8_t {
> US_LEFT = 0,
> US_MID = 1,
> US_RIGHT = 2,
> IR_LEFT = 3.
> IR_RIGHT = 4
> };
> const uint8_t TIME_DIFF {5};
>
> const uint8_t SONAR_NUM {3};
> const uint8_t IR_NUM {2};
> const uint8_t BUFF_SIZE {SONAR_NUM + IR_NUM};
>
> const uint8_t MAX_DISTANCE {200};
> const uint8_t DIST_UNKNOWN {999);
>
> uint32_t cm[BUFF_SIZE{0}; // will initialize entire array to 0
>
> I'd change the names to be lower case the same as regular variables. Using
> an *enum struct* can cause challenges since it doesn't convert to regular
> integers so must be cast: *uint8_t(US_LEFT)*. But it is safer if you want
> to enforce its use only as the enum.
> -73 -
> *Rud Merriam K5RUD*
> *Mystic Lake Software* <http://mysticlakesoftware.com/>
>
> On 12/17/21 3:28 PM, John Gauthier via DPRGlist wrote:
>
> 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 <paradug at gmail.com>
>> *Sent: *Thursday, December 16, 2021 11:46 PM
>> *To: *Chris Netter <netterchris at gmail.com>
>> *Cc: *Pat Caron <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 <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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