what is the principle of converting Ticks in to seconds

RE: what is the principle of converting Ticks in to seconds

Susheel Nuguru — Wed, 17 Feb 2016 10:42:11 GMT

I am not sure ... i think there are some regulators acting in between, and i do not want to guess about them :(

RE: what is the principle of converting Ticks in to seconds

karan — Wed, 17 Feb 2016 10:38:38 GMT

Thank you for your kind reply yes i have checked that my VDD is showing 2.62 approx( for battery 3.0v) am getting 58 percent battery and for USB power supply am getting 2.90volt as VDD and (90 percentage battery) and also i verfied wth the above formula the obtained results are corrct but the real problem is why there is lot ofdifference between Battery votlage(2.62volt) and USB power (2.90volt) almost 0.30volt drop is due to the DIODE VOLTAGE DROP or do you have any idea why this votlage drop happening between these two power supply?

RE: what is the principle of converting Ticks in to seconds

Susheel Nuguru — Wed, 17 Feb 2016 10:26:24 GMT

I have updated the formula for 3.0 V max. if 3000mV is max and 2100mV is min, then diff is 900mV hence percentage is ((mvolts -2100) * 100 ) /900 which is same as (mvolts -2100)/9

To verify if the percentage is right, you need to check your battery voltage with a multimeter and check if it is correct to (shown_percentage *9) +2100 mV.

RE: what is the principle of converting Ticks in to seconds

karan — Wed, 17 Feb 2016 09:56:11 GMT

is there is any other ways to check the battery voltage inorder to make sure the measurement is correct how do you calculate the function like that percentage +12 is there is any idea behind in it?

RE: what is the principle of converting Ticks in to seconds

karan — Wed, 17 Feb 2016 09:54:14 GMT

thanks for your kind reply after i have modified those function am getting 68perrcentage as batteryv oltage but how can i make sure that value is correct? however the CR2032 maximumvoltage will be 3V as per the datasheet so can we put 1800 instead of 2100 if i put like that am getting 93 percentage battery for 1800 value and 68 percent for 2100 value in the above formula

RE: what is the principle of converting Ticks in to seconds

Susheel Nuguru — Wed, 17 Feb 2016 09:40:12 GMT

depends on your chip. From the info center i can read that nrf51422 has suppy range of 1.8V-3-6V. This means that 2.1V must be 0% because this is low of CR2032 battery. and 3.3 must be 100% (because most coin cell comes with 3.0V output).

in app_util.h change the function battery_level_in_percent like below

static __INLINE uint8_t battery_level_in_percent(const uint16_t mvolts)
{
    // We assume 3000 mV is 100% and 2100 mv (dead CR2032) is 0%  = (((mvolts - 2100) * 100)/900);
    return ((mvolts - 2100) /9);
}

from the above you can tell that your suppy voltage is (percentage * 9) + 2100 Remember that CR2032 will never get to 1.8V i guess, but the above example

and change BATTERY_LEVEL_MEAS_INTERVAL to appropriate interval you need. Remember that first time the drop will be from 100% to down drastically because we start the program with assumption of 100%

RE: what is the principle of converting Ticks in to seconds

karan — Wed, 17 Feb 2016 09:24:50 GMT

Thanks for your kind brief information about this point could you tell me some ideas how to implement the fucntion in order to see the real battery voltage something around 80 to 90percent atleaset because i would like to broadcast the battery votlage to the MASTER control panel in real time ?i have checked via UART putty terminal in the ADC handler fucntion am getting adc_result value as 57 and batt_level_milli_volts as 809 and percentage in battery as 0 hardly i did nto understand how this value are interrelated (all measurements are done via USB power)

RE: what is the principle of converting Ticks in to seconds

Susheel Nuguru — Wed, 17 Feb 2016 09:16:46 GMT

@Karan: I change the proximity app to check the battery level every 10 s

#define BATTERY_LEVEL_MEAS_INTERVAL         APP_TIMER_TICKS(10000, APP_TIMER_PRESCALER)

When you connect your MCP to the device ->discover services->enable services then you will see that MCP will start to get notifications every 10 s for the battery level change. Note that the notification is only sent of the battery level has changed from the previous notified value.

@prabhudurai: The voltage always starts with 100% when your app starts irrespective of what the actual voltage on your device. After the first sample is taken BATTERY_LEVEL_MEAS_INTERVAL time after your enable the services, then it will then check the actual voltage and tell you that the real value.

15% does not mean that your battery is very old or dying.

 *           The discharge curve for CR2032 is non-linear. In this model it is split into
 *           4 linear sections:
 *           - Section 1: 3.0V - 2.9V = 100% - 42% (58% drop on 100 mV)
 *           - Section 2: 2.9V - 2.74V = 42% - 18% (24% drop on 160 mV)
 *           - Section 3: 2.74V - 2.44V = 18% - 6% (12% drop on 300 mV)
 *           - Section 4: 2.44V - 2.1V = 6% - 0% (6% drop on 340 mV)

RE: what is the principle of converting Ticks in to seconds

MARTIN FR — Tue, 16 Feb 2016 09:46:16 GMT

Hello aryan thanks for your kind feedback could you tell me what is the reason for the voltage drop of 15percent while using battery? what is the necessary modifcations to be done for battery level function? you mean the battery_level _function is showing how much voltage drop instead of how much battery left?

RE: what is the principle of converting Ticks in to seconds

karan — Tue, 16 Feb 2016 09:41:37 GMT

How you find the battery voltage getting dropped to 15 percent?

RE: what is the principle of converting Ticks in to seconds

Susheel Nuguru — Tue, 16 Feb 2016 08:13:21 GMT

I have run the SDK10 example and i also see the same thing what you saw. Will look into it now. Edit

I have now run the battery example on SDK 10 with usb and coin cell battery. You are right, the coin cell battery drops to 15% because the voltmeter shows 2.64V and according to battery_level_in_percent() this is 15%. If you want your battery level to behave differently, you need to change this function.

RE: what is the principle of converting Ticks in to seconds

MARTIN FR — Mon, 15 Feb 2016 16:11:17 GMT

Hello aryan am using SDK 10 i have checked with the ble_app example without changing the code but still it is showing 15 percent only and if i tried with SDK 9 this function is stoppign the entire executions

err_code = app_timer_create(&m_battery_timer_id, APP_TIMER_MODE_REPEATED,

                            battery_level_meas_timeout_handler);
APP_ERROR_CHECK(err_code);

do i ahve change the timer functionality for SDK 9 or it has to be put in application timers?

RE: what is the principle of converting Ticks in to seconds

Susheel Nuguru — Mon, 15 Feb 2016 15:45:41 GMT

i have to try out this example, i will do that tomorrow when i get back to office. New coin cell battery should be showing 90% if not there is some problem. Which SDK versions did you use?

RE: what is the principle of converting Ticks in to seconds

MARTIN FR — Mon, 15 Feb 2016 13:53:52 GMT

Hello aryan i am also looking for this kind issue? i do want to focus on USB power my aim is to measure Battery percentage so i focus only on battery my real problem is why the battery percentage showing 12 percent ? it is the new battery so it has to show around atleast 90 percent how i can find the real time battery percentage? what should i do inorder to get exact battery percentage?

RE: what is the principle of converting Ticks in to seconds

Susheel Nuguru — Mon, 15 Feb 2016 13:22:42 GMT

At first the application is started with 100% battery because the actual ADC sample is started in battery_level_meas_timeout_handler after 120 seconds from enabling this notification. After this value the actual pin is sampled and then in the ADC_IRQHandler you use battery_level_in_percentto convert the sampled value.

For your CR2032, the 15% might be correct value, but it is displayed after 120 seconds because that is when the first sample is taken. If you want this to be updated faster, you need to change BATTERY_LEVEL_MEAS_INTERVAL.

For your USB, you cannot use battery_level_in_percent in ADDC_IRQHandler as this is for CR2032. You need to write your own interpreting function in case of USB.

RE: what is the principle of converting Ticks in to seconds

karan — Mon, 15 Feb 2016 11:53:23 GMT

thanks for your kind reply more importantly onething which i didnot understand is if i power the development board via USB it is showing intially 100 percent and then later it is going down to 57percent and in opposite case if i provide the power supply to the circuit via Battery CR2032 it is showing initially 100percent and after certain interval it is dropped down to 15percent i dont understand why basically VDD pin is indicating2.65 volt (Battery supply ) and 2.88volt for USB power supply but the result of the battery percentage values shown in the MCP is strange can you tell me some informations about this two points? and diode voltage drop plays a vital role in this two case?

RE: what is the principle of converting Ticks in to seconds

Susheel Nuguru — Mon, 15 Feb 2016 11:24:21 GMT

prescaler is only needed to be changed if your timeout is more than 512 seconds. So here you you can use 0 as prescaler.

This below code can be used to see if ADC sample value drops to 30% and send notification.

    uint32_t err_code;
    uint16_t adc_value;
    uint8_t  percentage_batt_lvl;
    uint16_t batt_lvl_in_milli_volts;
    nrf_adc_conversion_event_clean();
    nrf_adc_stop();
    
    adc_value = nrf_adc_result_get();
    
    
    batt_lvl_in_milli_volts = ADC_RESULT_IN_MILLI_VOLTS(adc_value);
    
    percentage_batt_lvl     = battery_level_in_percent(batt_lvl_in_milli_volts);

    if(percentage_batt_lvl <= 30) {
    err_code = ble_bas_battery_level_update(&m_bas, percentage_batt_lvl);
    if (
        (err_code != NRF_SUCCESS)
        &&
        (err_code != NRF_ERROR_INVALID_STATE)
        &&
        (err_code != BLE_ERROR_NO_TX_PACKETS)
        &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
       )
    {
        APP_ERROR_HANDLER(err_code);
    }
   }

RE: what is the principle of converting Ticks in to seconds

karan — Mon, 15 Feb 2016 11:14:04 GMT

Thanks aryan for your brief explanation the reason i would to change the presclar value is to measure the battery level and send the notifications to user if the battery level drops to 30 percent and so for doing that what is the best possible ways to do that? karan (12 mins ago)editconvert to answer

RE: what is the principle of converting Ticks in to seconds

karan — Mon, 15 Feb 2016 10:53:14 GMT

RE: what is the principle of converting Ticks in to seconds

Artucas — Mon, 15 Feb 2016 10:31:36 GMT

I haven't, but this link might help you: battery service

RE: what is the principle of converting Ticks in to seconds

Susheel Nuguru — Mon, 15 Feb 2016 10:26:54 GMT

Assuming you are using nRF51 and using APP_TIMER (RTC1).

You initialize the APP_TIMER using the prescaler. lets say that the prescaler is 0 then your timer generates 32768 ticks per second.

The macro given in app_timer.h converts the milliseconds to number of ticks.

#define APP_TIMER_TICKS(MS, PRESCALER)\
            ((uint32_t)ROUNDED_DIV((MS) * (uint64_t)APP_TIMER_CLOCK_FREQ, ((PRESCALER) + 1) * 1000))

Above you see that if MS = 120000 and prescaler 0, which is 120 seconds then you will get Ticks = ((120000*32768)/(0+1)*1000) rounded up to integer = 3932160 ticks. This is telling you that the timer will put 3932160 (0X3c0000) in RTC compare register and when RTC is started and is running for this many ticks, then it will be 120 seconds.

Does this answer your question?

RE: what is the principle of converting Ticks in to seconds

karan — Mon, 15 Feb 2016 10:23:27 GMT

Thank you so much for your kind reply and its helpful for me have you worked on the battery measurement or battery notifications ?

RE: what is the principle of converting Ticks in to seconds

Artucas — Mon, 15 Feb 2016 10:11:11 GMT

I have a periodical temperature measurements in my application. For that i set up a timer like this:

// Start application timers.
err_code = app_timer_start(m_temperature_timer_id, TEMPERATURE_MEAS_INTERVAL, NULL);
APP_ERROR_CHECK(err_code);

And my TEMPERATURE_MEAS_INTERVAL is defined as follows:

// Temperature measurement interval
#define TEMPERATURE_MEAS_INTERVAL APP_TIMER_TICKS(RTC_IRQ_PERIOD_MS, APP_TIMER_PRESCALER)

Here RTC_IRQ_PERIOD_MS = 5000. (With APP_TIMER_PRESCALER set to zero.) This configuration gives me measurement interval of 5s. So by changing RTC_IRQ_PERIOD_MS you can configure your timeout in milliseconds. Hope it helps.