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--- en:pfw:dht22 [2025-06-26 01:38] – [SDA Protocoll] mka
+++ en:pfw:dht22 [2025-06-27 12:05] (current) – [Implementation for RP2040 using a PIO block] mka
@@ Line 1: / Line 1: @@
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-====== DHT22 Protocol ======
+====== DHT22 ======
 The DHT22 module is a low-cost digital temperature and humidity sensor. It utilizes a capacitive humidity sensor and a thermistor to measure the surrounding air and outputs a digital signal via a single data pin. It's known for its wider measurement range and higher accuracy compared to its predecessor, the DHT11.
@@ Line 56: / Line 56: @@
 {{ :en:pfw:dht22-bit_lesen_mit_2xmoon.png?nolink |The timing is critical. So, it's correct now. Here we read a "0"}}
-===== Implementation =====
+====== Implementation for TI's Launchpad ======
-==== Pseudocode ====
-<code>
-Function: Pio    ( -- )  \ set port I/O function. SDA --> P1.0
-Function: wakeup ( -- )  \ notify sensor to prepare the data
-Function: @data  ( -- sun moon hum tmp chk chksum )  \ get sensor data
-  get response time of sensor, store in register 'sun' (just for testing)
-  get startpulse duration, store in register 'moon'
-loop
-     read bit using 'moon' based delay
-     lshift bit into array xx yy zz
-loop
-     lshift array  \ adjust xx yy zz --> hum tmp chk
-  calculate chksum
-Function: (dht22)  ( -- sun moon hum tmp chk chksum ) \ wake up and read sensor
-Function:  dht22   ( -- )  \ print temperatur and humidity
-Function:  test    ( n -- ) \ multiple readings
-    n loop  dht22
-</code>
-==== Source Code for Launchpad - and what it was used for.====
-[[en:pfw:dht22-msp430g2553-noforth|DHT22 with Launchpad MSP430G2553 and noForth]]
 This program was used to test DHT22 modules before installation. The DHT22 modules were tested for functionality at room temperature, pre-sorted in this way, and then frozen in a bag of moist sand in the freezer and tested again. One module displayed incorrect temperature values in frost conditions, the display of negative values did not comply with the specifications.
+[[en:pfw:dht22-msp430g2553-noforth|DHT22 for Launchpad MSP430G2553 and noForth]]
-==== Numerical representation of the measured values ====
-=== Humidity ===
+====== Implementation for RP2040 ======
-The first 16 bits coming from the DHT22 are the relative humidity in tenths of a percent. They can be processed directly with the 16-bit noForth and correspond to a positive integer. Rounded to whole digits for display purposes.
+[[en:pfw:dht22-rp2040-nofortht|DHT22 for the Raspberry Pi Pico Board RP2040 and noForth t]] using a PIO block
-Here is an excerpt from the noforth source code:
-<code>
-: .hum ( hum -- )   10 / . ." %rel" space  ;
-</code>
-=== Temperature ===
-The next 16 bits are the temperature in tenths of a degree Celsius. Temperatures from zero degrees and higher can be processed directly using the 16-bit noForth; they correspond to a positive integer.
-Temperatures below zero degrees are represented by the DHT22 as follows: The MSB of the 16-bits is set, but otherwise the temperature is specified as a positive integer. This number format //does not correspond// to the two's complement of noForth. Here, the MSB must first be evaluated to determine the sign. The sign is prepended for output. The measured value can then be further processed as a positive integer.  Whole degrees are displayed to the left of the decimal point, tenths to the right. The unit °C is specified.
-<code>
-: .tmp ( tmp -- )
-  dup hx 8000 and hx 8000 =  \ check MSB
-      if [char] -
-      else [char] +
-      then emit
-  hx 7fff and ( tmp -- +tmp )    \ reset MSB
-/mod 3 .r [char] . emit .    \ --> TTT.T
-  [char] f decemit  [char] C emit  \ print °C
-  space
-  ;
- </code>
-  * This is already included in the following source code.\\
-  * And here you can see how this was discovered: [[en:pfw:dht22tmpformat|The temperature format of the DHT22]]
-===== Background Information =====
-=== MSP430G2553 ===
+PIO stands for //Programmable Input Output//. You can program the PIO blocks with the [[en:pfw:assemblers_pio-assembler|noforth t PIO Assembler]].
+====== Background Information ======
+  * How this was discovered: [[en:pfw:dht22tmpformat|The temperature format of the DHT22]]
   * [[https://www.ti.com/lit/ug/slau144j/slau144j.pdf|MSP430x2xx Family guide SLAU144J.PDF]]
   * [[https://www.ti.com/lit/ds/symlink/msp430g2553.pdf|MSP430G2553 datasheet SLAS735J.PDF]], port data on page 49ff
+  * [[https://home.hccnet.nl/anij/nof/noforth.html| noforth.html - find your version, docmentation,  tool.f and asm.f here.]] All about noForth.
+  * [[en:pfw:whatisapioblock|What is a PIO block?]]
-=== All about noForth ===
+====== Aids ======
-[[https://home.hccnet.nl/anij/nof/noforth.html| noforth.html - find your version, docmentation,  tool.f and asm.f here.]]
----
-=== Source code editor ===
+MK:\\
 I like //Notepad Next// for Linux, a cross-platform, reimplementation of //Notepad++//.
-https://github.com/dail8859/NotepadNext
+https://github.com/dail8859/NotepadNext\\
-=== Terminal ===
 To work with the embedded noForth system I use //e4thcom// by Manfred Mahlow.
-https://wiki.forth-ev.de/doku.php/projects:e4thcom
+https://wiki.forth-ev.de/doku.php/projects:e4thcom\\
+Sometimes I also use Windows and Teraterm, for example, to log longer MCU outputs to a file. I also prefer it for testing parts of the source code using copy and paste.\\
-Sometimes I also use Windows and Teraterm, for example, to log longer MCU outputs to a file. I also prefer it for testing parts of the source code using copy and paste.
+In this project I used a Logic Analyzer by AZDelivery, 8 CH, 24MHz. (Amazon)\\
-=== Logic Analyser ===
-AZDelivery Logic Analyzer 8 CH, 24MHz. (Amazon)\\
 //PulseView// is a Qt-based logic analyzer and oscilloscope GUI for sigrok.
----