Difference between revisions of "Arduino notes"

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Getting started . . .
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Getting started:
  
 
*  https://playground.arduino.cc/Learning/CommandLine . . . mentions PlatformIO "ecosystem" and specific Linux ready command line tools for working with Arduino
 
*  https://playground.arduino.cc/Learning/CommandLine . . . mentions PlatformIO "ecosystem" and specific Linux ready command line tools for working with Arduino
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Specific Arduino projects . . .
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The ATMEGA328P processor used in Arduino Uno boards:
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*  http://www.microchip.com/wwwproducts/en/ATmega328p . . . the ATMEGA328P processor used in Arduino Uno boards
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Specific Arduino projects:
  
 
*  https://www.hackster.io/niesse/water-level-ultrasonic-sensor-with-lorawan-c2cf55
 
*  https://www.hackster.io/niesse/water-level-ultrasonic-sensor-with-lorawan-c2cf55
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*  https://www.arduino.cc/en/Tutorial/HelloWorld
  
  
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FreeRTOS port to Arduino . . .
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FreeRTOS port to Arduino:
  
 
*  https://github.com/feilipu/Arduino_FreeRTOS_Library
 
*  https://github.com/feilipu/Arduino_FreeRTOS_Library
  
  
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== Arduino Wire Library ==
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2018-05-21 - Monday, looking at /usr/share/arduino/libraries/Wire/utility/twi.c, routine twi_writeTo() error codes:
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<pre>
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177 /*
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178  * Function twi_writeTo
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179  * Desc    attempts to become twi bus master and write a
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180  *          series of bytes to a device on the bus
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181  * Input    address: 7bit i2c device address
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182  *          data: pointer to byte array
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183  *          length: number of bytes in array
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184  *          wait: boolean indicating to wait for write or not
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185  *          sendStop: boolean indicating whether or not to send a stop at the end
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186  * Output  0 .. success
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187  *          1 .. length to long for buffer
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188  *          2 .. address send, NACK received
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189  *          3 .. data send, NACK received
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190  *          4 .. other twi error (lost bus arbitration, bus error, ..)
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191  */
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192 uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait, uint8_t sendStop)
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193 {
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194  uint8_t i;
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195
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196  // ensure data will fit into buffer
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197  if(TWI_BUFFER_LENGTH < length){
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198    return 1;
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199  }
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  .
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  .
 +
  .
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</pre>
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According to the oscilloscope the I2C communications are running at about 192kHz, a little fast.  Here is documentation at the Arduino site about setting the I2C clock rate:
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*  https://www.arduino.cc/en/Reference/WireSetClock  . . . Wire.setClock() class method not found on localhost!
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Another place where SCL frequency may be set . . .
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<pre>
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user@localhost:/usr/share/arduino/libraries/Wire$ grep -nr lock ./*
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./Wire.cpp:84:  // perform blocking read into buffer
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./Wire.cpp:139:  // transmit buffer (blocking)
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./utility/twi.c:85:  SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR))
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./utility/twi.c:467:      // sends ack and stops interface for clock stretching
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</pre>
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2022-06-13
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OpenMV IDE and Arduino Nano:
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<ul>
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*  https://blog.arduino.cc/2021/08/24/power-of-python-for-arduino-nano-rp2040-connect-and-nano-33-ble/
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</ul>
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<!-- comment -->
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== References ==
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<!-- comment -->
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<!-- comment -->
 
<!-- comment -->
 
<!-- comment -->

Latest revision as of 20:08, 13 June 2022



Getting started:


The ATMEGA328P processor used in Arduino Uno boards:


Specific Arduino projects:


FreeRTOS port to Arduino:


Arduino Wire Library

2018-05-21 - Monday, looking at /usr/share/arduino/libraries/Wire/utility/twi.c, routine twi_writeTo() error codes: 

177 /*
178  * Function twi_writeTo
179  * Desc     attempts to become twi bus master and write a
180  *          series of bytes to a device on the bus
181  * Input    address: 7bit i2c device address
182  *          data: pointer to byte array
183  *          length: number of bytes in array
184  *          wait: boolean indicating to wait for write or not
185  *          sendStop: boolean indicating whether or not to send a stop at the end
186  * Output   0 .. success
187  *          1 .. length to long for buffer
188  *          2 .. address send, NACK received
189  *          3 .. data send, NACK received
190  *          4 .. other twi error (lost bus arbitration, bus error, ..)
191  */
192 uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait, uint8_t sendStop)
193 {
194   uint8_t i;
195 
196   // ensure data will fit into buffer
197   if(TWI_BUFFER_LENGTH < length){
198     return 1;
199   }
   .
   .
   .


According to the oscilloscope the I2C communications are running at about 192kHz, a little fast. Here is documentation at the Arduino site about setting the I2C clock rate:

Another place where SCL frequency may be set . . . 

user@localhost:/usr/share/arduino/libraries/Wire$ grep -nr lock ./*
./Wire.cpp:84:  // perform blocking read into buffer
./Wire.cpp:139:  // transmit buffer (blocking)
./utility/twi.c:85:  SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR))
./utility/twi.c:467:      // sends ack and stops interface for clock stretching


2022-06-13

OpenMV IDE and Arduino Nano:


References

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