====== MPAINO K high-speed pulse output module ======

The K option module outputs the MCU's PWM waveform without filtering it into a DC signal. K provides six channels and K2 provides twelve. The selected module is assembled into the MPAINO product before shipment. Unlike the Y analog output module, this output is a 0–5V digital waveform; check that the receiving device accepts it.

{{ :en-us_products:mpaino-k-channels.svg?1000 |K, K2, and mixed Y/K channel numbers and shared Timer groups }}

===== Specifications =====

{{:en-us_products:mpaino-option-k-front.png?190|K pulse output module front}} {{:en-us_products:mpaino-option-k2-front.png?190|K2 second pulse output module front}}

PWM0–PWM5 on the K2 image are terminal labels on the second K module. Its additional program channels are 6–11.

^ Item ^ Description ^
| Option codes | K, K2 |
| Outputs per module | Six PWM channels |
| Output levels | LOW 0V; HIGH 5V |
| Maximum output current | 30mA per channel |
| Maximum frequency | 1MHz |
| Resolution | 16 bit |
| Maximum configuration | Two K modules, twelve channels; Y and K outputs together no more than twelve channels |

K outputs use the MCU GPIO signal directly. Do not connect a load exceeding 30mA or an input requiring another voltage directly. Use a suitable external driver for a motor, solenoid, or similar load.

===== Options and channel numbering =====

^ Configuration ^ K channels ^ ''PWM()'' / ''FDPWM()'' channel ^ ''analogWrite()'' channel ^ GPIO number ^
| K | 6 | 0–5 | 20–25 | D130–D135 |
| K2 | 12 | 0–11 | 20–31 | D130–D141 |
| YK / Y2K | 6 | 0–5 | 20–25 | D130–D135 |

These are three numbering schemes for **the same K outputs** with different functions. ''analogWrite(20, 128)'' addresses the first K output; ''analogWrite(0, 128)'' addresses the first Y analog output. ''PWM(0, ...)'' again addresses the first K output. One K and one or two Y modules can be ordered together, but K2 cannot be combined with Y. Match Arduino IDE's **High-Speed Pulse Output Module** and **Analog Output Module** options to the shipped configuration.

===== Shared Timers =====

^ Configuration ^ K channels ^ Internal Arduino PWM pins ^ Shared Timer ^
| K alone | 0–2 | D11, D12, D13 | Timer1 |
| K alone | 3–5 | D46, D45, D44 | Timer5 |
| Additional K2 | 6–8 | D5, D2, D3 | Timer3 |
| Additional K2 | 9–11 | D6, D7, D8 | Timer4 |
| YK / Y2K | 0–2 | D5, D2, D3 | Timer3 |
| YK / Y2K | 3–5 | D6, D7, D8 | Timer4 |

Three channels on one Timer can have different duty cycles, but share its frequency. The internal PWM pins change with the Y/K combination; match the program's logical channels to the product's shipped configuration.

===== Wiring and first measurement =====

  - Disconnect power and identify the PWM terminal and the GND in its terminal group.
  - Connect the receiving device's 0–5V PWM input and common GND according to the product's wiring diagram.
  - Do not feed external power into a PWM output or attach an overcurrent load directly.
  - Check the waveform frequency and duty with suitable test equipment before connecting the process load.

===== Example 1: Arduino analogWrite() =====

The first output of a K-only configuration receives approximately 50% duty. K's ''analogWrite()'' uses values 0–255, unlike Y's output range.

<code cpp>
const uint8_t pulseChannel = 20;  // analogWrite number of the first K output

void setup() {
}

void loop() {
  analogWrite(pulseChannel, 128);  // Output PWM at about 50% duty
  delay(500);
}
</code>

===== Example 2: frequency and duty =====

K-only CH0 and CH1 share Timer1. Both run at 1kHz, with different duties.

<code cpp>
void setup() {
  PWM_RESET();  // Reset K-output PWM Timer state
  FDPWM(0, 1000, 25.0F);  // K CH0: 1kHz, 25% duty
  FDPWM(1, 1000, 75.0F);  // K CH1: 1kHz, 75% duty
}

void loop() {
}
</code>

''PWM_RESET()'' can reset other PWM outputs using the same Timers. Run it only when the connected load is in a safe state.

===== Example 3: a fixed pulse count =====

This sends 100 pulses at 1kHz and 50% duty on K CH0. ''NPWM()'' must be called repeatedly until output completes, so there is no ''delay()'' in ''loop()''.

<code cpp>
void setup() {
  PWM_RESET();  // Reset PWM state before starting the pulse train
  NPWM_BEGIN(0, 1000, 50.0F, 100);  // Prepare 100 pulses on CH0
}

void loop() {
  NPWM(0);  // Advance and finish the prepared pulse train
}
</code>

===== Troubleshooting =====

^ Symptom ^ Check ^
| No waveform | Check the K module and board option, PWM/GND terminals, and the channel number expected by the chosen function. |
| Unexpected frequency | Check whether another channel in the same Timer group changed the frequency. |
| Mixed Y/K product differs from K-only wiring | The internal PWM pin mapping changes with the Y/K combination. Check the shipped configuration and module terminal labels. |
| Fixed pulse train never finishes | Call ''NPWM()'' repeatedly on the same channel after ''NPWM_BEGIN()''; avoid delays in the loop. |

===== Related pages =====

  * [[en-us_commands:reference:pwm|PWM()]] · [[en-us_commands:reference:fdpwm|FDPWM()]] · [[en-us_commands:reference:npwm_begin|NPWM_BEGIN()]] · [[en-us_commands:reference:npwm|NPWM()]]
  * [[en-us_products:mpaino_x|X analog input]] · [[en-us_products:mpaino_f|F PT100 input]] · [[en-us_products:mpaino_y|Y analog output]]
  * [[en-us_products:mpaino|← MPAINO Series options]]