Thursday, May 14, 2015

Hottop KN-8828B-2K+

Beginning with Artisan version 0.9.3, support for the Hottop KN-8828B-2K+ home roaster is available. Besides other improvements over previous models, that machine features a USB port that can be used to connect this roaster to a computer running Artisan without requiring any additional hardware or software (see Controlling a Hottop). Artisan allows logging the temperatures from both factory-installed thermocouples of the KN-8828B-2K+ allowing Artisan to read the Environmental Temperature (ET) and Bean Temperature (BT). Artisan also can read the fan speed data (0-10 in increments of 10) and the heater level data (0-100 in increments of 1) from the machine. Finally, by defining some extra buttons and sliders on the Artisan side, it is also possible to fully take control over the machine, setting the heater, fan and even controlling the main motor, cooling tray and drop door. Using Artisan's alarm features it is then possible to run complex roast programs using time and temperature settings in a fully automatic mode if desired.

UPDATE (3.4.2018): Since v1.2 Artisan can be configured for the Hottop KN-8828B-2K+ with one click. Find out more on

1. Introduction

We have chosen to support the Hottop KN-8828B-2K+ in a generic way, following the Artisan philosophy to allows users to configure their roast logging environment based on their own needs and desires. To configure Artisan to work the way you want it to, we present the following four steps which cover all the configuration possibilities. Even if you do not wish to use them all, following along will help familiarize you with the way Artisan works and how powerful of a tool it can be.


2. Basic Setup

You have to install

  • Artisan (obviously)
  • VCP FTDI serial driver, for the communication between your computer and the Hottop serial chip. This is a virtual COM port that allows Artisan and the computer to communicate through the USB port and to "see" and "talk to" the Hottop. NOTE: Most Linux systems and Mac OS X 10.9 and later contain already support for the FTDI hardware and therefore no additional driver needs to be installed on those systems. Installing an additional driver might cause instabilities.

3. Reading from the KN-8828B-2K+

3.1 Device Assignment (menu Config >> Device)

  • ET/BT Tab
    • tick "Meter"
    • select "Hottop BT/ET"

  • Extra Devices Tab
    • add one extra device by pushing button Add
    • select device "Hottop Heater/Fan"
    • set "Label 1" to "Heater"
    • set "Label 2" to "Fan"


3.2 Serial Ports Configuration (menu Config >> Serial Port)

  • ET/BT Tab 
    • Comm Port: xx      (select while connected to roaster) 
    • Baud Rate: 115200
    • Byte Size: 8
    • Parity: N
    • Stopbits: 1
    • Timeout: 1

If all the above configurations are done and your computer is connected to the Hottop you should get the ET, BT, heater and fan readings shown on the Artisan LCDs and you are ready to go recording your first roast. The heater and fan settings are drawn as temperature curves in the range 0-100.

4. Advanced Configuration

4.1 Configure Rate-of-Rise, Smoothing and Projection

Add DeltaET and/or DeltaBT (RoR) curves and/or LCDs and configure the smoothing algorithm.
  • Extras Dialog (menu Tools >> Extras, Graph tab)
    • tick "DeltaET", "DeltaBT" under "Curves" and "LCDs"
    • Smoothing Curves: 2
    • Delta Span: 15s
    • Smooth Deltas: 10
    • tick "Project" to get a projection line drawn on the ET and BT curves based on the current RoR

4.2 Automatic CHARGE and DROP

Artisan can be configured to automatic recognize the CHARGE and DROP events based on the BT temperature drop. For the Hottop mode, the DROP event is registered automatically if the eject bean door is opened.

  • Events Dialog (menu Config >> Events)
    • tick "AutoCHARGE" to have the CHARGE event automatically be detected based on the rapid falling BT on adding the green beans
    • don't tick "AutoDrop", as DROP is automatically detected if the solenoid for the eject bean door is opened

UPDATE: the flag "Show" was renamed in recent version of Artisan to "Events", but kept the semantic of controlling the visibility of the custom events data.

4.3 Register Heater and Fan as Custom Events

  • hide Heater/Fan curves (menu Config >> Device, Extra Devices tab)
    • untick "Curve 1" and "Curve 2"

  • activate event quantifiers (menu Config >> Events, Quantifiers tab)
    • tick "Power" (second event type), set "Source" to "0xT1: Heater"
    • tick "Fan" (last event type), set "Source" to "0xT2: Fan", tick "Coarse"

  • ensure that custom events are drawn (menu Config >> Events, Config)
    • tick "Show"
    • set Bars to "Value"
    • set event name 2 to "Power" and name 4 to "Fan"

5. Taking Control

To control the Hottop you need to configure controls that send commands once activated.

5.1 Deactivate Quantifiers (menu Config >> Events, Quantifiers)

To avoid interactions (double registration of events) we deactivate the event quantifiers that we configured in the previous step. The button and slider command actions will directly generate the corresponding events instead.

  • untick Power (0xT1: Heater) / Fan (0xT2: Fan) event quantifier


5.2 Add Control Buttons (menu Config >> Events, Buttons)

  • add buttons to turn on and off the Motor and the stirrer as well as to open and close the door using the action "Hottop Command" and the corresponding command string one of  (see the screen shot below). For example, the first two lines in the screen shot below are for the Drum Motor ("MOTOR"). One command turns it on ("1") and the other turns it off ("0").
    • motor(0)
    • motor(1)
    • solenoid(0)
    • solenoid(1)
    • stirrer(0)
    • stirrer(1)
  • add also custom buttons to change fan or heater setting the same way (or alternatively define sliders as explained below)
    • fan(x)      with an integer 0-10
    • heater(x)   with an integer 0-100
  • select button and text colors to differentiate the actions

From Artisan v0.9.8 on it is also possible to define buttons that change the event values relative to the previous values.

5.3 Add Heater and Fan Sliders (menu Config >> Events, Sliders)

  • tick "Power" (second event type), set action to "Hottop Heater"
  • tick "Fan" (last event type), set action to "Hottop Fan"


5.4 DROP Action (menu Config >> Events, Config)

To have the Hottop act the same as the factory default upon the discharge of the beans (turning off the heater, run the fans at the maximum speed, keep the drum turning, opening the bean door, and activating the stirrer) one can attach a corresponding action on the Artisan "DROP" button.

  • DROP button section: select "Hottop Command", and enter the action string

If you have configured the custom event button and the sliders correctly, you should end up with an Artisan main window like the following.

UPDATE: in recent versions of Artisan the blue "Control" button is only visible if activated by ticking the "Control" flag within the Device Assignment dialog (menu Config >> Device.., first tab).


  • Event buttons can be shown and hidden by pressing the 'b' key.
  • Event sliders can be shown and hidden by pressing the 's' key.
  • Start Artisan by pressing the green "ON" button on top of the main window.
  • Control mode is only active in super-user mode that can be activated by a right-click on the Timer LCD in the right upper corner of the main window.
  • After starting Artisan, take control of the roaster from the Artisan interface by pressing the blue button on top of the main window labeled "Control." Pressing control will always start the drum motor.
  • CAUTION: If control is switched off (by pressing the "Control" button once again), depending on the current temperatures reported by the sensors, the machine might stop completely. Take care!
  • A safety mechanism implemented on the Artisan side will eject the beans if the bean temperature reaches 212C/413F in control mode.
  • Full automation can be achieved via alarm programs that operate slider and button events (incl. standard events like DROP). These will take place automatically based on time and temperature limits that you set.

A video on YouTube showing a roast with the Artisan controlled Hottop 2K+ by roastmasterscoffee and another one by NapoHBarista TV.