_intPin1 and _intPin2

Question

_intPin1 and _intPin2

vvirag opened this issue 6 years ago · 15 comments

The BMA280 class has a _intPin1 and _intPin2 member, which are set in the constructor.
However, I don't see them being read out afterwards. What are they used for then?

(I'm trying to port this code to another platform, and I'm not sure how to set up the interrupts to set the newData and newTap flags -- since I don't understand which pins should these interrupts coupled to.)

Thanks for any help!

Answer 1 · 2019-01-13T16:55:10.000Z

These serve no function in this implementation and can be removed.

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On Sun, Jan 13, 2019 at 7:15 AM Virag Varga ***@***.***> wrote: The BMA280 class has a _intPin1 and _intPin2 member, which are set in the constructor. However, I don't see them being read out afterwards. What are they used for then? (I'm trying to port this code to another platform, and I'm not sure how to set up the interrupts to set the newData and newTap flags -- since I don't understand which pins should these interrupts coupled to.) Thanks for any help! — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#2>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qm1d_g_QdiNaPeymhPM8ra6teEtyks5vC012gaJpZM4Z9N4X> .

Answer 2 · 2019-01-13T17:17:47.000Z

Yes, that's what I thought, thanks :)

I'm still puzzled though where the 4 and 1 come from regarding these lines:
#define intPin1 4 #define intPin2 1

-- since later the newData and newTap flags are getting set based on the interrupts when these 2 pins are rising.

Answer 3 · 2019-01-13T17:21:24.000Z

These are the GPIOs I am using for these BMA280 interrupts.

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On Sun, Jan 13, 2019 at 9:17 AM Virag Varga ***@***.***> wrote: Yes, that's what I thought, thanks :) I'm still puzzled though where the 4 and 1 come from regarding these lines: #define intPin1 4 #define intPin2 1 - since later the newData and newTap flags are getting set based on the interrupts when these 2 pins are rising. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qg3etWxpwOcgXsUxvvqFIvKUxfN9ks5vC2o7gaJpZM4Z9N4X> .

Answer 4 · 2019-01-13T17:31:11.000Z

Ah, wait, you're saying these are external GPIOs on the Arduino that you use when you actually want to read out (from the application code) the tap/move states of the accelerometer?

Answer 5 · 2019-01-13T17:39:31.000Z

Yes, I am using the interrupts as input to the STM32L4 MCU for data ready and tap detection (or other functions). I am just saying _intPin1 and _intPin1 serve no purpose in the .cpp file or functions since the interrupts are managed in the main sketch.

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On Sun, Jan 13, 2019 at 9:31 AM Virag Varga ***@***.***> wrote: Ah, wait, you're saying these are external GPIOs on the Arduino that you use when you actually want to read out (from the application code) the tap/move states of the accelerometer? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qhUz3Lt_dFhaciFE4UuTSF9mRO_5ks5vC21fgaJpZM4Z9N4X> .

Answer 6 · 2019-01-13T17:43:48.000Z

I'm sorry maybe I still don't get it right. This means you are polling accelerometer data from the MCU, right? Meaning that something - that is unrelated to the accelerometer - will pull up the pin1 (=1 on the MCU) and pin2 (=4 on the MCU) whenever you decide you want to read out the accelerometer status.

Or I'm completely wrong..? :)

Answer 7 · 2019-01-13T17:50:29.000Z

Completely wrong. The BMA280 interrupts are configured to pulse whenever data is ready or tap is detected. This lets the MCU know it is time to read the data, handle the taps, etc. Interrupts 101? Look at Arduino.cc for a tutorial....

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On Sun, Jan 13, 2019 at 9:43 AM Virag Varga ***@***.***> wrote: I'm sorry maybe I still don't get it right. This means you are polling accelerometer data from the MCU, right? Meaning that something - that is unrelated to the accelerometer - will pull up the pin1 (=1 on the MCU) and pin2 (=4 on the MCU) whenever you decide you want to read out the accelerometer status. Or I'm completely wrong..? :) — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qjCZU9yFt9beb1GvFn-Xu4oFSjc6ks5vC3BUgaJpZM4Z9N4X> .

Answer 8 · 2019-01-13T18:01:21.000Z

I have some clue about interrupts, and I'm not even working on Arduino. And yes, it seemed strange, but I just still don't understand how exactly are the

BMA280 interrupts configured.

As far as I can tell that configuration is happening in the BMA280::initBMA280 function. But there are lots of magic (hexa)numbers there, and even though the BMA280 documentation is in front of me, I haven't been able to completely understand it.

And this goes back to my original question on where the 1 and 4 are coming from (as defined in the .ino). And how those values are reflected in that initBMA280 method.

Answer 9 · 2019-01-13T18:04:32.000Z

Last time. Interrupts are outputs from the BMA280 (must be configured according to the BMA280 data sheet) specified in initBMA280 and are inputs to the MCU, which GPIO pins (in this case pin 1 and pin 4) must be specified and configured in the main sketch. This is true whether you are using Arduino or anything else.

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On Sun, Jan 13, 2019 at 10:01 AM Virag Varga ***@***.***> wrote: I have some clue about interrupts, and I'm not even working on Arduino. And yes, it seemed strange, but I just still don't understand how exactly are the BMA280 interrupts configured. As far as I can tell that configuration is happening in the BMA280::initBMA280 function. But there are lots of magic (hexa)numbers there, and even though the BMA280 documentation is in front of me, I haven't been able to completely understand it. And this goes back to my original question on where is the 1 and 4 are coming from (as defined in the .ino). And how those values are reflected in that initBMA280 method. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qq4qXHpNYAUl9Yaorv7eyuhU-Ksbks5vC3RygaJpZM4Z9N4X> .

Answer 10 · 2019-01-13T18:10:56.000Z

I appreciate your answers, really. And I agree with everything you just said, that's all clear.

I guess I just don't see where (which line in your code) the MCU GPIO1 and MCU GPIO4 gets connected to the INT1 and INT2 interrupts of the BMA280.

Is my question more clear this way?

Answer 11 · 2019-01-13T18:48:58.000Z

Oh my, it just hit me. This connection-configuration that I was looking for in the code.. It's not in the code, right? You just have them physically connected, right? Ah.. Sry for the troubles.

Answer 12 · 2019-04-16T13:20:38.000Z

looking at page 50 of the data sheet, i don't think this "destination[0] = ((int16_t)rawData[1] << 8) | rawData[0];" is correct. that will give you a 16 bit number (should be 14 bits).; the lower 2 bits of the LSB are as follow: bit 1- undefined, bit 0: new_data flag. should it be something like: destination[0] = ((int16_t)(rawData[1] << 6) | (rawData[0]>>2));" ?

Answer 13 · 2019-04-16T16:20:37.000Z

In the main loop we divide by 4: BMA280.readBMA280AccelData(accelCount); // get 14-bit signed accel data // Now we'll calculate the accleration value into actual g's ax = (float)accelCount[0]*aRes/4.0f; // get actual g value, this depends on scale being set ay = (float)accelCount[1]*aRes/4.0f; az = (float)accelCount[2]*aRes/4.0f; this is the same as >> 2. So either way you want to do this is fine.

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On Tue, Apr 16, 2019 at 6:20 AM cleonb32 ***@***.***> wrote: looking at page 50 of the data sheet, i don't think this "destination[0] = ((int16_t)rawData[1] << 8) | rawData[0];" is correct. that will give you a 16 bit number (should be 14 bits).; the lower 2 bits of the LSB are as follow: bit 1- undefined, bit 0: new_data flag. should it be something like: destination[0] = ((int16_t)(rawData[1] << 6) | (rawData[0]>>2));" ? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qoh-XSwDINcvRvhe5KJFEbdrfLvCks5vhc4mgaJpZM4Z9N4X> .

Answer 14 · 2019-04-16T18:44:28.000Z

" I could not find your reference to 8192 (0x2000)." ??Huh??

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On Tue, Apr 16, 2019 at 11:32 AM cleonb32 ***@***.***> wrote: thanks. looking at the datasheets I could not find your reference to 8192 (0x2000). — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qhO8pVDgQcmkQV2Z1r8PhkycQ3Ijks5vhhcugaJpZM4Z9N4X> .

Answer 15 · 2019-04-16T19:05:54.000Z

14-bit signed integer means maximum value of the data is 2^13.

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On Tue, Apr 16, 2019 at 11:54 AM cleonb32 ***@***.***> wrote: "_aRes = 2.0f/8192.0f;// per data sheet" i could not find 8192.0f in the datasheet — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#2 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGY1qvZa33_Ee92beDZHISGmENRFQURZks5vhhx1gaJpZM4Z9N4X> .