Hi, I need support to increase the sample rate speed of ADS1115 using the library "Adafruit_ADS1015.h" and an ESP32 module. I am using the example included in the library for differential measure. The only changes made are: Serial.begin(115200) gain rate: setGain(GAIN_FOUR) setDataRate(RATE_ADS1115_860SPS) using HEX number 0x00E0 Using command "micros()" before and after the line... results = ads.readADC_Differential_0_1(); ...I misured the time to take the value from my sensor: ~7.5ms. With 860 sps the time should be ~1.2ms. Have you any suggestion to reach the higher speed? it is not mandatory use the same library, but it is almost mandatory use 1 module ADS1115! Surfing in the web I found this post where "pylon" suggest to change the library: see the ref. link You will have to change the library: On line 154 replace ADS1015_REG_CONFIG_DR_1600SPS by ADS1015_REG_CONFIG_DR_3300SPS. On line 104 replace ADS1115_CONVERSIONDELAY by 1. So you might get up to 860 Hz. Someone can explaine me where I found the lines mentioned in the post? I didn't found in the library adafruit these commands!!! Thanks!

Here is code that I modified from the example. /*************************************************************************** * Based on example sketch Conv_Ready_Alert_Pin_Controlled * from the ADS1115_WE library * * See the example for more omformation I have deleted most of the * comments to limit the length of the text * * This sketch shows how you can use the alert pin as conversion ready alert pin. * It works in continuous mode * Please note that you need to enable the alert pin with setAlertPinMode. Choose any * parameter except ADS1115_DISABLE_ALERT. * * Further information can be found on: * https://wolles-elektronikkiste.de/ads1115 (German) * https://wolles-elektronikkiste.de/en/ads1115-a-d-converter-with-amplifier (English) * ***************************************************************************/ #include // from "Streaming by Mikal Hart" in library manager #include #include #define I2C_ADDRESS 0x48 volatile bool convReady = false; ADS1115_WE adc = ADS1115_WE(I2C_ADDRESS); #ifdef ESP8266 // setup for esp8266 const uint8_t interruptPin = D5; // pin2 is default SDA // Interrupt service routine for external interrupt // Make sure it is in RAM void IRAM_ATTR convReadyAlert(){ convReady = true; } #else // assume an AVR UNO, MEGA, classic NANO etc const uint8_t interruptPin = 3; void convReadyAlert(){ convReady = true; } #endif struct ConvertData { uint32_t cvtTime; float voltage; } ; ConvertData readData[4]; unsigned long oldTime,currTime; void setup() { Wire.begin(); Wire.setClock(400000); Serial.begin(9600); pinMode(interruptPin, INPUT_PULLUP); if(!adc.init()){ Serial.println("ADS1115 not connected!"); } /* Set the voltage range of the ADC to adjust the gain * Please note that you must not apply more than VDD + 0.3V to the input pins! */ adc.setVoltageRange_mV(ADS1115_RANGE_6144); //comment line/change parameter to change range /* Set the inputs to be compared */ adc.setCompareChannels(ADS1115_COMP_0_GND); //comment line/change parameter to change channels adc.setAlertPinMode(ADS1115_ASSERT_AFTER_1); //needed in this sketch to enable alert pin (doesn't matter if you choose after 1,2 or 4) /* Set the conversion rate in SPS (samples per second) */ adc.setConvRate(ADS1115_860_SPS); //comment line/change parameter to change SPS adc.setMeasureMode(ADS1115_CONTINUOUS); // the conversion ready alert pin also works in continuous mode adc.setAlertPinToConversionReady(); //needed for this sketch Serial.println("ADS1115 Example Sketch - Continuious, Conversion Ready Alert Pin controlled"); Serial.println(); attachInterrupt(digitalPinToInterrupt(interruptPin), convReadyAlert, FALLING); oldTime = micros(); } uint8_t count; void loop() { count = 0; while(count<4) { // get 4 readings if(convReady){ currTime = micros(); readData[count].voltage = adc.getResult_V(); // alternative: getResult_mV for Millivolt readData[count].cvtTime = currTime - oldTime; count++; // get next reading oldTime = currTime; convReady = false; //reset ready indicator } } Serial<<"Time uSec Voltage"<<endl; for (uint8_t i=0;i<4;i++) { // display 4 readings Serial <<readData[i].cvtTime <<" "<< readData[i].voltage <<endl; } delay(1000); // delay to change voltage convReady = false; //reset ready indicator oldTime = micros(); } Here is some output from an ESP8266. Time uSec Voltage 80 0.15 1215 0.15 1216 0.15 1216 0.15 Time uSec Voltage 78 0.28 1216 0.28 1215 0.28 1216 0.28 Time uSec Voltage 80 1.41 1216 1.41 1216 1.42 1216 1.42 Time uSec Voltage 76 2.81 1216 2.81 1215 2.81 1216 2.82 Time uSec Voltage 74 3.28 1216 3.28 1216 3.28 1216 3.28 The first time is low because apparently a conversion was almost complete. The rest are about 1.216msec which is a sample rate of about 822 SPS

[image] rosincesco: Is it possible to rise up the sampling frequency of the ADS1115 to 1 or 10kHz ? No. You will be fortunate if you can realize the maximum rate of 860 SPS.

I am sorry for misunderstanding, that question was only the title of the linked page!!!! I know that the max is 860 sps. My question is: how to reach it? what I have to modify from original example of the library? tkx

Please do not modify your original post after getting feedback. It makes the thread difficult to impossible for others to follow. Post your code, using code tags, and post a link to the exact ADS library you are using. If you print anything in the sample loop, you probably cannot achieve the expected sample rate.

Maybe if you explain for what application you need that sampling. The most of the applications are good for the ADS1115. If you need some more "powerfull" in sampling, check another options with SPI interface like ADS5484

[image] anon94801460: Please do not modify your original post after getting feedback. It makes the thread difficult to impossible for others to follow. I am sorry! I am measuring the signal 50Hz of +-1V from a sensor SCT013-050. Here the library: Adafruit_ADS1x15 Here the sketch used, at the end I wrote the speed in us I found the same speed also with the "Serial.println" inside the "for" #include #define RATE_ADS1115_860SPS (0x00E0) Adafruit_ADS1115 ads; /* Use this for the 16-bit version */ int16_t results; unsigned long t[30]; void setup(void) { Serial.begin(115200); Serial.println("Getting differential reading from AIN0 (P) and AIN1 (N)"); Serial.println("+/- 1.024V 1 bit = 0.5mV 0.03125mV"); ads.setGain(GAIN_FOUR); // 4x gain +/- 1.024V 1 bit = 0.5mV 0.03125mV ads.setDataRate(RATE_ADS1115_860SPS); if (!ads.begin()) { Serial.println("Failed to initialize ADS."); while (1); }} void loop(void) { delay(2000); for (int i = 0; i < 16; i++) { t[i] = micros(); results = ads.readADC_Differential_0_1(); //Serial.println(micros()-t[i]); } for (int i = 0; i < (16-1); i++) { Serial.println(t[i+1]-t[i]); } } /* * Results: * 32715us setDataRate = default * 7495us setDatarate = 860sps */ [image] sanplatano89: If you need some more "powerfull" in sampling, check another options with SPI interface like ADS5484 Yes, I know that SPI is better. Is it impossible to reach the speed 860sps by I2C with ADS1115?

[image] rosincesco: Is it impossible to reach the speed 860sps by I2C with ADS1115? Undoubtedly not. The data sheet is a legal document, and it clearly states that 860 SPS is supported. You are assuming that your particular configuration, leaving most of the defaults intact (I2C clock rate, ADS1x15 defaults) intact, should reach that rate, and that is probably incorrect. Note that the differential conversion requires reading two channels, and the default setting is "single shot". You may have better luck reading a single channel after setting it to continuous conversions. Also set the I2C clock to 400 kHz. Read the data sheet carefully for more options, such as high speed I2C communications.

I come back with a lot of trial done during my few free time! Best performance reached with ADS1X15 Rob Tillaart library (ADS1X15_LIB_VERSION: 0.3.7) with following code: #include "ADS1X15.h" #include ADS1115 ADS(0x48); int clockFrequency = 800000; int16_t results[30]; unsigned long t[30]; void setup() { Serial.begin(115200); Serial.print("ADS1X15_LIB_VERSION: "); Serial.println(ADS1X15_LIB_VERSION); Wire.begin(); Wire.setClock(clockFrequency); ADS.begin(); ADS.setGain(4); // 1.024 volt ADS.setDataRate(7); // fast ADS.setMode(1); // 0=continuous mode; 1=single } void loop() { delay(2000); for (int i = 0; i < 5; i++) { t[i] = micros(); results[i] = ADS.readADC(0); } for (int i = 0; i < (4); i++) { Serial.print(results[i]); Serial.print("\t"); Serial.println(t[i+1]-t[i]); } Serial.println(""); } Here below the time to read the sensor in micro seconds with some modifications: * clockFrequency = 100000; & setMode(0); 8986 9000 9000 9000 * clockFrequency = 400000; & setMode(0); 8268 7985 8000 8000 * clockFrequency = 400000; & setMode(1); 6709 6690 6689 6683 * clockFrequency = 800000; & setMode(1); 6572 6596 6587 6591 * clockFrequency = 2000000; & setMode(1); 6573 6586 6589 6591 * clockFrequency = 3400000; & setMode(1); 6572 6582 6589 6583 Thoughts and questions: According to the technical datasheet of ADS1115 https://www.ti.com/lit/ds/symlink/ads1115.pdf (SPS output rate using ads1115 - #2 by gilshultz) are defined 3 levels of clock speed: 100kHz, 400kHz (fast mode) and 3.4MHz (high speed mode). I reach the best performance at 800kHz with 150 SPS. Higher freq doesn't give advantages. Are there any command to speedup really the clock? 860 SPS are very far from my situation! where is the bottleneck? any suggestions? Could be that the ADS1115 goes in power-down state and goes on slowly? How to avoid to enter in power-down state? Thanks for your support

[image] rosincesco: ADS.setMode(1); // 0=continuous mode; 1=single Why have you set single shot mode? What happens with continuous?

with continuous mode the time is higher. In my post I have written the results with some combinations: with freq 400kHz setMode(0) is slower than setMode(1), 8 vs 6,7 us!

Once again "use the source" - look at the library source code to see what is happening. What processor are you running? In single shot mode the library code does a yield() call. On a classic AVR based Arduino this is basically a no-op. On an ESP8266 this gives up control of the processor to the background processing (WiFi etc) for an indeterminate amount of time. Not sure what an ESP32 does, since it has dual cores and the background tasks usually run on a different core than "user" code. In continuous mode the library code does an unconditional delay of 8ms, which limits the max rate to 125 SPS.

ADS1115 high speed data rate

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anon94801460 November 5, 2022, 1:52pm 9

Why have you set single shot mode? What happens with continuous?

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ADS1115 high speed data rate

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