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====== Solenoid Closed Loop Control Demo ======

The **ADuCM3029_demo_cn0415** provides a solution for controlling and monitoring solenoid actuator current, using an **EVAL-CN0415-ARDZ** shield installed on an **EVAL-ADICUP3029** base board. The user interface is implemented as a command line interface (CLI) through a serial UART connection. The project is created using **CrossCore Embedded Studio** and **GNU ARM compiler**.
===== General Description/Overview =====

The circuit can be divided into four parts for the purpose of analyzing interaction with the software project: The supply block, the sense block, the actuator block, and the overcurrent fault / reset block.

The supply block consists of DC-DC converters and protection circuits. This block does not interact with the software. 

Overcurrent fault and Overcurrent Reset block, controlled by general-purpose input/output (GPIO) pins on **ADICUP3029**. If the solenoid current exceeds a resistor-programmed threshold, a comparator trips off the MOSFET gate driver and notifies software via a GPIO signal. The user can then re-enable the driver once the fault condition is removed.

The sense block, consisting of a 0.1Ω  current sense resistor, sense amplifier, filtering, and 14-bit Analog to Digital converter (ADC). The ADC is connected to the ADICUP3029 via Serial Peripheral Interface (SPI)


The voltage fed to the ADC with respect to current passing through the solenoid is given by the equation:
<code>
       VADC = Isolenoid * Rsense * 20       Isolenoid - Current through solenoid    
                                            Rsense    - Sense resistor (0.1Ω)  
</code>
The code output by the ADC is then calculated:
<code>
                                            VADC - Voltage on the ADC input
       CODE = (VADC * 2^14) / Vref          CODE - Code output by the ADC
                                            Vref - Reference voltage of the ADC
</code>
Here **Vref** is the reference voltage of the ADC and depends on the chosen supply. **If** the **12V on P1** was selected the supply voltage of the ADC will be 5V and the corresponding reference is **4.096V**. **If** the ADC is powered from Arduino with **3.3V** the reference will be **2.048V**.

So the ADC code with respect to current sense will be:
<code>
       CODE = (Isolenoid * Rsense * 20 * 2^14) / Vref
</code>

The actuator block, consisting of a logic-level to MOSFET driver. The logic signal is driven by the **ADICUP3029**’s PWM peripheral, allowing the the effective voltage across the solenoid to be varied.

The software implements several functions with the sense and actuator blocks. PWM frequency and duty cycle can be controlled directly. This mode of operation would normally be combined with an outer feedback loop in a control system. One example would be a system in which the solenoid controls  air pressure, that is in turn measured by a pressure sensor, which is then used to determine a new duty cycle value that brings the pressure closer to the desired setpoint.

A PID control loop allows the solenoid current to be accurately controlled, compensating for variations in supply voltage and coil resistance. This mode of operation allows for optimum drive current for 2-state solenoids, minimizing power dissipation. An additional function allows a higher initial “pull in” current to be applied for a short time, after which current drops back to a lower “hold” current.

{{ :resources:eval:user-guides:eval-adicup3029:reference_designs:pid_controller_equation.png?nolink | PID equation}}

Using the data gathered form the sense block the a **PID controller** is implemented that can be used to set a specific current value or duty cycle. To use the **PID controller** it must be first tuned with the right values of **Kp**, **Ki** and **Kd**. Various methods can be used for tunning. The proposed method, which is easy, but does not yield perfect results, is: 
  - Start increasing **Kp** constant while keeping **Ki** and **Kd** at 0. Increase **Kp** until the actuation time is reasonable and the current overshoot is within 5% of the wanted value.
  - Start increasing **Ki** constant until the actuation time is reasonable and the current overshoot is within 5% of the wanted value.
  - Pick **Kd** as 25% (1/4) of **Ki**.

A dither function allows a low-frequency AC signal to be superimposed, minimizing mechanical “stiction” in proportional solenoid applications.

===== Demo Requirements =====

The following is a list of items needed in order to replicate this demo.
  * Hardware
    * EVAL-ADICUP3029
    * EVAL-CN0415-ARDZ
    * Mirco USB to USB cable
    * PC or Laptop with a USB port
    * Solenoid actuator
    * 12V and 1A limited power supply
  * Software
    * CrossCore Embedded Studio (2.6.0 or higher)
    * ADuCM302x DFP (2.0.0 or higher)
    * ADICUP3029 BSP (1.0.0 or higher)
    * Serial Terminal Program (Required for running in release mode only)
      * Such as Putty or Tera Term
    * [[https://github.com/analogdevicesinc/EVAL-ADICUP3029/tree/master/projects/ADuCM3029_demo_cn0415 | AduCM3029_demo_cn0415 demo application]]

===== Setting up the Hardware =====

  - Connect **EVAL-CN0415-ARDZ** board to the **EVAL-ADICUP3029**. {{ :resources:eval:user-guides:eval-adicup3029:reference_designs:cn0415_adicup3029_dock.jpeg | CN0415 docked on ADICUP3029 }}
  - Connect a micro-USB cable to **P10** connector of the **EVAL-ADICUP3029** and connect it to a computer.
  - Connect a solenoid actuator to the **P8** connector with the positive wire on pin 1 and negative wire on pin 2.
  - Connect a 12V power supply to the **P1** connector with the positive wire on pin 1 and negative wire on pin 2.{{ :resources:eval:user-guides:eval-adicup3029:reference_designs:cn0415_fully_connected.jpeg | CN0415 power up }}
  - Turn on power supply.
===== Configuring the Software =====

The configuration parameters can be found in the **config.h** file.

**vref** - Reference voltage of the **ADC** set by supply method as described above. Set to **4.096** if the supply is the 12V on **P1** or to **2.048** if supply is the **Arduino** 3.3V.

^ Supply voltage         ^ vref value  	^
| 3.3V                  | 2.048 	|
| 12V                   | 4.096         |

<code>
   /* Reference voltage of the ADC */
   float vref = 4.096;
</code>

===== Outputting Data =====

{{page>/wiki/common#serial_terminal_setup&nofooter&noheader}}

==== Available commands ====

Typing **help** or **h** after initial calibration sequence will display the list of commands and their short versions. Below is the short command list:

^Type ^ Command                   ^ Description 								^
|System| //h//                  | Display available commands 	|
|  | //rst//                | Reset controller, parameters and faults | 
|  | //stts//               | Show application status and parameters | 
|  | //clb//                | Run calibration sequence | 
|Control  | //f//\\ ex: **f 5000<enter>**\\ (set frequency to 5kHz)              | Set frequency to the specified value\\ <//freq//> = value of the new frequency\\ 1Hz to 4MHz frequency is possible.|
|  | //d//\\ ex: **d 5234<enter>**\\ (set duty cycle to 52.34%.)                  | Set duty cycle to the specified value\\ <//duty//> = value of the new duty cycle\\ The duty cycle is from 0 representing 0% and 10000 representing 100%. |
|  | //r//                  | Read and display the value of the ADC |
|  | //ad//                 | Activate PWM dither functionality | 
|  | //rd//                 | Deactivate PWM dither functionality | 
|  | //df//\\ ex: **df 50<enter>**\\ (set dither freq. to 50Hz)                 | Set dither frequency to the given value\\ <//freq//> = value of the new frequency\\ Recommended maximum value of the PWM frequency divided by 10. | 
|  | //da//\\ ex: **da 200<enter>**\\ (set dither amplitude to 2%)                 | Set dither amplitude\\ <//duty//> = value of the amplitude in duty cycle variation\\ Any value between 0 and 10000, same as duty cycle.\\ Recommended to be lower than the lowest value needed\\ for the duty cycle to be 0 or full scale. | 
|PID  | //ap//                 | Activate PID controller | 
|  | //rp//                 | Deactivate PID controller | 
|  | //kp//\\ ex: **kp 5000.0<enter>**\\ (set kp to 5000)                 | Set PID Kp constant\\ <//kp//> = value of the new Kp constant\\ From zero to maximum number represented by a 32 bit float value. | 
|  | //ki//\\ ex: **ki 1.5<enter>**\\ (set ki to 1.5)                 | Set PID Ki constant\\ <//ki//> = value of the new Ki constant\\ From zero to maximum number represented by a 32 bit float value. | 
|  | //kd//\\ ex: **kd 0.25<enter>**\\ (set kd to 0.25)                 | Set PID Kd constant\\ <//kd//> = value of the new Kd constant\\ From zero to maximum number represented by a 32 bit float value. | 
|  | //spf//\\ ex: **spf 100<enter>**\\ (set sample freq. to 100Hz)                | Set PID sampling frequency\\ <//freq//> = value of the new frequency\\ Recommended to be at most equal with the dither frequency. | 
|  | //sps//\\ ex: **sps 2500<enter>**\\ (setpoint to 25%)                | Set PID set point(hold value)\\ <//sp//> = new hold value in A or 0.01%(duty cycle)\\ From 0 to 1 amperes or from 1 to 10000 as duty cycle. | 
|Digital  | //dson//               | Set digital solenoid high | 
|  | //dsof//               | Set digital solenoid low | 
|Proportional  | //pss//\\ ex: **pss 2500<enter>**\\ (setpoint to 25%)                | Set and activate proportional solenoid\\ <//val//> = value of the current or duty cycle\\ from 0 to 1 amperes. | 


{{ :resources:eval:user-guides:eval-adicup3029:reference_designs:wiki_pic.png?nolink | Terminal example}}

===== Obtaining the Software =====

There are two basic ways to program the ADICUP3029 with the software for the CN0415.
  - Dragging and Dropping the .Hex to the Daplink drive
  - Building, Compiling, and Debugging using CCES

Using the drag and drop method, the software is going to be a version that Analog Devices creates for testing and evaluation purposes.  This is the EASIEST way to get started with the reference design

Importing the project into CrossCore is going to allow you to change parameters and customize the software to fit your needs, but will be a bit more advanced and will require you to download the CrossCore toolchain.  

The software for the **ADuCM3029_demo_cn0415** can be found here:

<WRAP round 80% download>
Prebuilt CN0415 Hex File
  * [[https://github.com/analogdevicesinc/EVAL-ADICUP3029/releases/download/Latest/ADuCM3029_demo_cn0415.hex| AduCM3029_demo_cn0415.Hex]]
Complete CN0415 Source Files
  * [[https://github.com/analogdevicesinc/EVAL-ADICUP3029/tree/master/projects/ADuCM3029_demo_cn0415| AduCM3029_demo_cn0415 Source Code]]
 
</WRAP>


===== How to use the Tools =====

The official tool we promote for use with the EVAL-ADICUP3029 is CrossCore Embedded Studio.  For more information on downloading the tools and a quick start guide on how to use the tool basics, please check out the [[resources:eval:user-guides:eval-adicup3029:tools|Tools Overview page.]]

==== Importing ====

For more detailed instructions on importing this application/demo example into the CrossCore Embedded Studios tools, please view our [[resources:eval:user-guides:eval-adicup3029:tools:cces_user_guide#how_to_import_existing_projects_into_your_workspace|How to import existing projects into your workspace]] section.

==== Debugging ====

For more detailed instructions on importing this application/demo example into the CrossCore Embedded Studios tools, please view our [[resources:eval:user-guides:eval-adicup3029:tools:cces_user_guide#how_to_configure_the_debug_session_for_an_aducm3029_application|How to configure the debug session]] section.

==== Project Structure ====

The program is composed of three main parts:
  - Board setup, with initialization;
  - Calibration;
  - Main process.

{{ :resources:eval:user-guides:eval-adicup3029:reference_designs:cn0415_sw_main_flowchart.png?nolink | Software main flow chart}}

The boards initial parameters can be given in the software in the main function or the **FLASH_INIT_PARAMETERS** define in the **config.h** file can be uncommented and the relevant parameters can be changed in program from the command line and the program will retain these parameters in the non-volatile memory.
The program initializes timers and UART, SPI, GPIO and FLASH controllers.

{{ :resources:eval:user-guides:eval-adicup3029:reference_designs:cn0415_sw_board_setup_flow.png?nolink | Software board setup flow chart}}

**Calibration** is done to minimize full scale error. It sets control signal to **logic "1"** and measures the current, then prompts the user for a manual measurement with a precision tool. The difference between these two measurements is stored and used in calculating future values from ADC codes.

{{ :resources:eval:user-guides:eval-adicup3029:reference_designs:cn0415_sw_calibration_flow.png?nolink | Software calibration flow chart}}

The **main process** is the infinite loop in which the program implements **CLI**, **PID** and **dither** functionality. The **UART** is used for the **CLI** and three different timers implement the **PWM** signal, the **PID** periodic calculation and the **dither** functionality.

{{ :resources:eval:user-guides:eval-adicup3029:reference_designs:cn0415_sw_process_flow.png?nolink | Software process flow chart}}

// End of Document //
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