[Dprglist] Arduino Code Troubles
Rud Merriam
rudmerriam at gmail.com
Fri Dec 17 14:06:55 PST 2021
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 <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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