There are ~30 Knowledge Base Articles (KBAs) in the Sensors section of the forum covering multiple sensors products. Sometimes, it's difficult to search for the information that you're interested in, especially when you don't know if that exists or not.
To simplify this task we have created a Sensors Knowledge Base Article List which has all the KBAs divided into sub-topics. This list only contains KBAs which are meaningful today, so you won't find anything related to legacy products. This is to avoid confusing our customers into reading material which is no longer applicable.
My application is: detect day versus night, indoors, in a room with south facing windows. I am exploring the Si1133 to measure UVA. I can put the detector within 10 feet of the windows, high and facing down so the detector gets reflected UV, and never gets direct sunlight, and gets only reflected artificial lights from typical room lighting of about 400 lux white, fluorescent light. My understanding is the window glass will transmit about 50% of UVA, that the sky will scatter significant UVA, that night sky has no UVA, and that artificial lights produce negligible UVA.
Might that work? Do you have any suggestions re diffuser, physical filters, parameters of the Si1133, and which set of diodes to use? My plan is to read only the UV diode.
I want to estimate sun time by detecting sundown and sunset, despite noise from artificial lights. I don't need accuracy. I plan to take samples over many days. I understand that the weather and season will have an effect.
What impedance will the LED pins have when the circuit is powered down?
More precise, if Si115x is powered from an regulated power domain (which could be turned off) while the IR-LED is powered directly from the battery.omeglexender
What happens with the LED input on the Si115x if the power supply to the circuit is shut of when the IR-LED still is powered from the battery.
Is there a risk for current leakage through the LED that eventually could drain the battery, if so how large would that leakage be.
Or is the design of the current sink regulator done so that a high impedance is guaranteed?
In this situation is it recommended to have the pull-up resistors connected to the regulated power domain which Si115x is powered from or is there any reason to have the resistors connected directly to the battery together vid the LED?
However when I try to force measurements from the Si1133 every 1 second, even 3 seconds, the ALS stops updating its latest data after 20-30 seconds. I found out that the program hangs while waiting for REG_IRQ_STATUS register to signal that the channel measurements are completed; specifically line 838:
/* Check if the measurement finished, if not then wait */
retval += read_register(REG_IRQ_STATUS, &response);
while ( response != 0x0F ) {
wait_ms(5);
retval += read_register(REG_IRQ_STATUS, &response);
}
Is this because I am forcing a measurement too quick? When I force measurements every 10 seconds the REG_IRQ_STATUS register does change after the measurement is finished and the program takes longer to hang but it still does eventually. How fast can we poll for a measurement? Our applications requires us to make an ALS reading every 1-2 seconds. How can we go about this? Is there a work around for this? Thanks in advance for your help!
I have an analog temperature sensor (TMP36GSZ-REEL-see datasheet here) and it is properly connected to an analog pin for reading its output.
The Arduino sketch (firmware) works just fine. Everything actually works fine except for two things:
If I plug more components in the circuit, like for example connecting an LED in parallel, temp readings go up for 1 degree (Celsius).
From time to time the readings go crazy (like 80°C or 100°C), although it's never that hot in here.
The connection is like this: from the Arduino's 5V pin to the sensor positive lead. Then, from the sensor's negative lead to the GND pin in Arduino. And finally, from the middle lead to the A1 analog reading pin.
Why are situations 1 and 2 happening? Is this normal?
I have some problems on software reset of Si1153. On some boards, the response0 register stays to 0x4E (suspend mode instead of sleep mode). When i power off the board, all gets fine.
We are using an Si7057 in our device to measure the temperature. However we observed an offset between 0.2 and 0.4 degrees compared to older devices in the same environment. The temperature range observed is between 25 and 40 degrees and the offset seems to remain fairly constant. We observed the offset in 30 sensors so far. We are looking for an explanation, but we could not find any.
We checked the decoding of the temperature code, but we could not find an error. We use the following C code to compute the temperature:
Unless I am mistaken, our implementation conforms almost exactly to the specification in the data sheet. Is this implementation correct?
Could this in any way be explained by measurement errors/device variability of the sensors themselves? +.3 degrees would be just within the specification, but for calibrated sensors we expected a somewhat more random distribution across devices and values roughly centered around 0.
I use the Simplest, Basic Performance Mounting Technique. The setting are: ADC gain mode of 1, 128 A/D samples (128 SW Gain and 50ms HW Gain), Decimation Filter Setting 3, 16 bits output registers, 7 bits to shift right after SW accumulation. Using Forced Conversion Mode without THRESHOLD.
The output reading I got are 0X0C50, 0X0D68 at indoor environment. If I use the formula :
UV index = k(m × Input2 + Input) which k=0.0104, m=0.00391
I can't get the reasonable UV index result from the output reading. Also I got 0XFFFF when I put the SI1133 under the sun.
I am working on a device using two Si1153 sensors on the same I2C bus. One of the sensors has LED2 tied to ground to force it to use the alternate I2C address.
The two sensors are configured identically (the same configuration function is called for each sensor): Each sensor is configured for proximity measurement on channel 0, and ALS measurement on channel 1; LED1 and LED3, not LED2, are used for proximity measurements; and each is in autonomous mode. Both sensors are reporting measurement data fine, except the proximity measurements on the sensor using the alternate address are not working. Values close to the maximum (> 63000) are always reported).
Proximity measurements work fine for the sensor using the standard I2C address. ALS measurements work fine for both sensors. The issue is only with proximity measurements on the sensor with LED2 tied to ground.
When using the alternate I2C address, does LED2 have to be pulled low only during startup, then set high in order for proximity measurements to work, even if not using LED2, or is there some other area I should explore?
I am wondering why the raw value for proximity channel changes when the light is turned off/on (or day-night switch)? Namely, when the light is turned on, the value increases immediately, while after turning off light the value decreases exponentially. The relative change in reading could be more than 50% (with parameters integration time is 48,8 us, Photodiode IR large, Signal Range Low). Any idea why this happens and how this should be resolved? On figure Prox stands for Proximimty (black line), and ALS stands for ambient light signal (blue line).
Our company has signed NDA. At present, the microcontroller uses efm32pg1, the sensors are si117x and bma255, the program is the latest, and has successfully displayed the heart rate value. I would like to ask if bma255 can be replaced by bma421 and other accelerometers.
Could you support me on how to compensate the IR response of the visible-light photodiode measurement and how to calculate the lux value of the measured visible light?
Our company has purchased si1175e2 and signed NDA. Recently, there is a problem in debugging with efm32pg1. After eliminating the possibility of chip damage, we found that there is a problem in the sample code. I didn't weld bma255, but in the program use_ accelerometer=0
1. Under low power consumption, the test results are not accurate and sensitive
2. In the two lamp States, the default ppgsamplerateus = 5000, which will make the lamp off after the program runs for 10s. If the ppgsamplerateus is increased, the lamp will always be on, unlike the sampling state.
Please ask what may be the cause of the problem. The current si117xHRM's software version is V2.2. If there is an update, please provide the latest efm32pg1 sample code. Thank you.
SI7020 is sitting on our board, it is directly powered by 3.3V coming from X-NUCLEO-LPM01A (directly connected to GND and VDD of SI7020, no any other current flow path).
Software:
I am running STM32-CUBEMONITOR-POWER PC utility connected to X-NUCLEO-LPM01A, MCU of my board is not talking to SI7020 (no I2C communication, MCU is not powered, just SI7020 is powered).
Question:
Why SI7020 consuming that much power in standby mode?
I believe SI7020 must be in standby mode, correct? Or, Is there any command to send that in standby mode (I didn't find any such command in the datasheet)?
Forum
Sensors Knowledge Base Article List
There are ~30 Knowledge Base Articles (KBAs) in the Sensors section of the forum covering multiple sensors products. Sometimes, it's difficult to search for the information that you're interested in, especially when you don't know if that exists or not.
To simplify this task we have created a Sensors Knowledge Base Article List which has all the KBAs divided into sub-topics. This list only contains KBAs which are meaningful today, so you won't find anything related to legacy products. This is to avoid confusing our customers into reading material which is no longer applicable.
Additionally please check out our Sensors training page -> https://www.silabs.com/support/training/sensors
Si1133 How to detect daylight indoors in south facing room while ignoring artificial lights, using UV.
My application is: detect day versus night, indoors, in a room with south facing windows. I am exploring the Si1133 to measure UVA. I can put the detector within 10 feet of the windows, high and facing down so the detector gets reflected UV, and never gets direct sunlight, and gets only reflected artificial lights from typical room lighting of about 400 lux white, fluorescent light. My understanding is the window glass will transmit about 50% of UVA, that the sky will scatter significant UVA, that night sky has no UVA, and that artificial lights produce negligible UVA.
Might that work? Do you have any suggestions re diffuser, physical filters, parameters of the Si1133, and which set of diodes to use? My plan is to read only the UV diode.
I want to estimate sun time by detecting sundown and sunset, despite noise from artificial lights. I don't need accuracy. I plan to take samples over many days. I understand that the weather and season will have an effect.
Si115x behavior at power down?
What impedance will the LED pins have when the circuit is powered down?
More precise, if Si115x is powered from an regulated power domain (which could be turned off) while the IR-LED is powered directly from the battery.omegle xender
What happens with the LED input on the Si115x if the power supply to the circuit is shut of when the IR-LED still is powered from the battery.
Is there a risk for current leakage through the LED that eventually could drain the battery, if so how large would that leakage be.
Or is the design of the current sink regulator done so that a high impedance is guaranteed?
In this situation is it recommended to have the pull-up resistors connected to the regulated power domain which Si115x is powered from or is there any reason to have the resistors connected directly to the battery together vid the LED?
Best Regard
Si1133 - How fast can I force a measurement for an ALS reading?
Hi there,
I managed to get the Si1133 to work with the example code found here https://os.mbed.com/teams/SiliconLabs/code/Si1133/rev/
However when I try to force measurements from the Si1133 every 1 second, even 3 seconds, the ALS stops updating its latest data after 20-30 seconds. I found out that the program hangs while waiting for REG_IRQ_STATUS register to signal that the channel measurements are completed; specifically line 838:
/* Check if the measurement finished, if not then wait */ retval += read_register(REG_IRQ_STATUS, &response); while ( response != 0x0F ) { wait_ms(5); retval += read_register(REG_IRQ_STATUS, &response); }Is this because I am forcing a measurement too quick? When I force measurements every 10 seconds the REG_IRQ_STATUS register does change after the measurement is finished and the program takes longer to hang but it still does eventually. How fast can we poll for a measurement? Our applications requires us to make an ALS reading every 1-2 seconds. How can we go about this? Is there a work around for this? Thanks in advance for your help!
Why is my analog temp sensor's signal so unstable?
I have an analog temperature sensor (TMP36GSZ-REEL-see datasheet here) and it is properly connected to an analog pin for reading its output.
The Arduino sketch (firmware) works just fine. Everything actually works fine except for two things:
If I plug more components in the circuit, like for example connecting an LED in parallel, temp readings go up for 1 degree (Celsius).
From time to time the readings go crazy (like 80°C or 100°C), although it's never that hot in here.
The connection is like this: from the Arduino's 5V pin to the sensor positive lead. Then, from the sensor's negative lead to the GND pin in Arduino. And finally, from the middle lead to the A1 analog reading pin.
Why are situations 1 and 2 happening? Is this normal?
Si1153-AA00-GM sw reset problem
Hi,
I have some problems on software reset of Si1153. On some boards, the response0 register stays to 0x4E (suspend mode instead of sleep mode). When i power off the board, all gets fine.
Below the initialisation procedure:
Should i retry reset command, until it returns to sleep mode ?
Regards,
Si7057 temperature offset?
We are using an Si7057 in our device to measure the temperature. However we observed an offset between 0.2 and 0.4 degrees compared to older devices in the same environment. The temperature range observed is between 25 and 40 degrees and the offset seems to remain fairly constant. We observed the offset in 30 sensors so far. We are looking for an explanation, but we could not find any.
We checked the decoding of the temperature code, but we could not find an error. We use the following C code to compute the temperature:
float SI705Y_CalcTemp(uint16_t tc)
{
return 175.0 * (float)tc / 65536.0 - 45.0;
}
Unless I am mistaken, our implementation conforms almost exactly to the specification in the data sheet. Is this implementation correct?
Could this in any way be explained by measurement errors/device variability of the sensors themselves? +.3 degrees would be just within the specification, but for calibrated sensors we expected a somewhat more random distribution across devices and values roughly centered around 0.
SI1133 UV-Index Calculation
SI1133 UV-Index Calculation
Hi, I am evaluating the SI1133 chip for UV-Index measurement. Based on the document, http://www.silabs.com/Support%20Documents/TechnicalDocs/AN968-Si1133-UV-Index-Sensor-Electrical-and-Optical-Design-Guide.pdf
I use the Simplest, Basic Performance Mounting Technique. The setting are: ADC gain mode of 1, 128 A/D samples (128 SW Gain and 50ms HW Gain), Decimation Filter Setting 3, 16 bits output registers, 7 bits to shift right after SW accumulation. Using Forced Conversion Mode without THRESHOLD.
The output reading I got are 0X0C50, 0X0D68 at indoor environment. If I use the formula :
UV index = k(m × Input2 + Input) which k=0.0104, m=0.00391
I can't get the reasonable UV index result from the output reading. Also I got 0XFFFF when I put the SI1133 under the sun.
Please help me on UV-Index Calculation. Thanks
Si1153-AB9x Proximity detection
Hi Silabs,
1. For 115xOPT-EXP-EVB, why is there an additional LED added to LED2 in the schematic diagram of Si1153-AB9x-GMR, is it necessary for actual use?
2. Can Si1153-AB9x-GMR be used as a distance sensor? How much accuracy can be achieved within 15cm?
3. In waveform viewer, as the hand approaches, the waveform rises, what data does the Y axis represent at this time?
many thanks.
Si1153 proximity measurement with LED2 tied to ground
I am working on a device using two Si1153 sensors on the same I2C bus. One of the sensors has LED2 tied to ground to force it to use the alternate I2C address.
The two sensors are configured identically (the same configuration function is called for each sensor): Each sensor is configured for proximity measurement on channel 0, and ALS measurement on channel 1; LED1 and LED3, not LED2, are used for proximity measurements; and each is in autonomous mode. Both sensors are reporting measurement data fine, except the proximity measurements on the sensor using the alternate address are not working. Values close to the maximum (> 63000) are always reported).
Proximity measurements work fine for the sensor using the standard I2C address. ALS measurements work fine for both sensors. The issue is only with proximity measurements on the sensor with LED2 tied to ground.
When using the alternate I2C address, does LED2 have to be pulled low only during startup, then set high in order for proximity measurements to work, even if not using LED2, or is there some other area I should explore?
Any hints would be appreciated.
SI115x
I am wondering why the raw value for proximity channel changes when the light is turned off/on (or day-night switch)? Namely, when the light is turned on, the value increases immediately, while after turning off light the value decreases exponentially. The relative change in reading could be more than 50% (with parameters integration time is 48,8 us, Photodiode IR large, Signal Range Low). Any idea why this happens and how this should be resolved? On figure Prox stands for Proximimty (black line), and ALS stands for ambient light signal (blue line).
Whether the algorithm of si117x can support other accelerometers
Si1145 lux conversion
Dear all,
Could you support me on how to compensate the IR response of the visible-light photodiode measurement and how to calculate the lux value of the measured visible light?
Thank you in advance!
On the problems of inaccurate heart rate results and slow response in the test code of efm32pg1 si1175
Our company has purchased si1175e2 and signed NDA. Recently, there is a problem in debugging with efm32pg1. After eliminating the possibility of chip damage, we found that there is a problem in the sample code. I didn't weld bma255, but in the program use_ accelerometer=0
1. Under low power consumption, the test results are not accurate and sensitive
2. In the two lamp States, the default ppgsamplerateus = 5000, which will make the lamp off after the program runs for 10s. If the ppgsamplerateus is increased, the lamp will always be on, unlike the sampling state.
Please ask what may be the cause of the problem. The current si117xHRM's software version is V2.2. If there is an update, please provide the latest efm32pg1 sample code. Thank you.
SI7020 is consuming 53.658 uA current in standby mode, that's a lot for low power design
According to the datasheet(https://www.silabs.com/documents/public/data-sheets/Si7020-A20.pdf), In standby mode SI7020 should consume 60nA but it's consuming around 53.658uA.
Hardware setup:
SI7020 is sitting on our board, it is directly powered by 3.3V coming from X-NUCLEO-LPM01A (directly connected to GND and VDD of SI7020, no any other current flow path).
Software:
I am running STM32-CUBEMONITOR-POWER PC utility connected to X-NUCLEO-LPM01A, MCU of my board is not talking to SI7020 (no I2C communication, MCU is not powered, just SI7020 is powered).
Question:
Why SI7020 consuming that much power in standby mode?
I believe SI7020 must be in standby mode, correct? Or, Is there any command to send that in standby mode (I didn't find any such command in the datasheet)?
Please, any idea/suggestion? Thanks!
-Anesh