mikepetro wrote:... I discovered that I had no jumper on ANLG2 (it wasnt shipped with one) so it was reading in C. I do not have a feel for roasting in C so I will need to pull the back cover off and install that jumper. Randy's HTC doc didnt really document the default or which pins to use, it just showed its existence, so I rolled the dice, they landed on C. Took me a while to find the pinout for the jumper, ended up finding it in your TC4 sketch readme, thank you for that.
Here it is if anyone needs it.
Pinout of ANLG2 port on TC4: +5V AN1 GND
Add jumper between AN1 and GND for Fahrenheit
I love the LED2 on this thing, it even works in non TC4-HTC mode. Wish I would have had that when I was figuring out the binary control of the P2.
I am anxious to try out your new PID mode...
An experimental PID and autotuner have been added to the Arduino Controller to explore the suitability of PID control of small electric coffee roasters. I want to make it very clear that these are experimental only and they may be removed from future versions of the program if they are not found to be useful.
I have very little experience of using PID control of a coffee roaster but, from my tests to date, I am not convinced that using a PID is the best way to control a small electrically heated roaster where a consistent bean mass can be used for all roasts. I believe that the current action table approach produces better control and superior roasts on Hottops and similar roasters. Despite my tests so far being unconvincing, I have decided to leave the PID in place for the time being in the hope that others will experiment with it and prove me wrong and advise how it should be used. Leaving the PID in place should not causes problems for people who do not wish to use it as, when the PID is turned off, everything is controlled by the action tables as in previous versions of the RoastLogger.
The action table approach relies on reasonable consistency in the relationship between the heater power setting and the RoR for any given bean temperature. With digital control of an electric heating element and reasonably consistent mains voltage this works very well and allows for rapid and accurate transition between one RoR and another in a way that PID control can not match, at least in my tests. I find that the PID either overshoots the required setting to an unacceptable extent, if aggressive tuning parameters are used, or takes an unacceptable number of minutes to achieve the required setting, neither of these is good for a coffee roaster. PID control would be beneficial where the bean mass varied significantly from roast to roast or for roasters where accurate digital control of the heater power was not possible such as gas heated roasters.
iginfect wrote:... What I'm doing to prolong 1st crack, and am still working on this as I have different beans to roast, is lowering my heat % before I hit 1st c to about 75% a few degrees before. I learn where 1st c is from prior roasts....
These notes are intended as a suggested method to help you get a feel for roasting in a Hottop fitted with a TC4/HTShield or TC4C/HTC and controlled by RoastLogger. They should be used in conjunction with the more detailed notes included in the RoastLogger manual.
The Hottop heating element has considerable thermal inertia. It takes about a minute for changes in heat input to produce a more or less full output change. Due to this it is necessary to predict what is going to happen and adjust settings at least a minute ahead of time.
The default action table settings, available from the Arduino Controller menu, are based on the results of testing by the beta testers and it is suggested you use these settings for your first roasts and then modify them as you find necessary. The intent of these settings is to level off the environment temperature at a temperature that results in a duration from the start of first crack to the end of the roast of approximately 3.5 to 4 minutes. This is achieved in the following stages:
1. Turn the heater down to about 65% at about 1 minute before first crack starts.
2. Turn the heater down to about 50% 60 seconds after first crack starts.
In more detail we can rewrite 1. and 2. above as:
1. Turn the heater down to a setting that will eventually levels off the environment temperature at a bean temperature that occurs about one minute before first crack starts. The intention is that the ET is level or slightly rising a minute or so after applying this setting.
2. Turn the heater down to a setting that will maintain a level environment temperature after first crack ends at about 60 seconds after first crack starts. The intention is that the ET is level or slightly rising a minute or so after applying this setting.
After carrying out a test roast using the default settings you can adjust the settings as follows:
a) If you find that the ET levels off and you get a duration from first crack start to end of roast of about 3.5 to 4 minutes then you are in the ballpark and can make minor adjustments to achieve your desired results.
b) If you find that the ET is falling/rising significantly during first crack then increase/decrease the heater power at 1. above as appropriate to achieve level or slightly rising ET.
c) If you find that the ET is falling/rising significantly after first crack ends then increase/decrease the heater power at 2. as appropriate to achieve level or slightly rising ET.
d) If you find the overall duration from first crack start to end of roast is too short then reduce the first heater turn down temperature this will reduce the maximum ET and extend the time from first crack start to end of roast.
e) If you find the overall duration from first crack start to end of roast is too long then increase the first heater turn down temperature this will increase the maximum ET and reduce the time from first crack start to end of roast.
I'm not following your discourse on PID mode. .....
I much prefer the action table approach of setting the heater and fan based on bean temperature before first crack and seconds elapsed after first crack start.
I find that the PID either overshoots the required setting to an unacceptable extent, if aggressive tuning parameters are used, or takes an unacceptable number of minutes to achieve the required setting, neither of these is good for a coffee roaster.