add test stepper

docs/Instruction/tips/stepper_TMC2208.md

+# Stepper Motor Driver TMC2208
+
+![](../images/stepper/TMC2208_front.jpg){width=300}
+![](../images/stepper/TMC2208_back.jpg){width=300}  
+[Digikey](https://www.digikey.jp/en/products/detail/trinamic-motion-control-gmbh/TMC2208SILENTSTEPSTICK/6873626)  
+
+## About
+ [Datasheet](https://www.trinamic.com/fileadmin/assets/Products/ICs_Documents/TMC220x_TMC2224_datasheet_Rev1.09.pdf)  
+ Ref. [youtube](https://www.google.com/search?q=TMC2208+how+to+use&rlz=1C5CHFA_enJP913JP913&oq=TMC2208+how+to+use&aqs=chrome..69i57j0i22i30.12837j0j7&sourceid=chrome&ie=UTF-8#kpvalbx=_Zp0dYqfAI9Pg2roP9bWQSA43)
+
+### Mode
+![](../images/stepper/modes.png)  
+
+- Mode 1: Standalone STEP/DIR Driver (Legacy Mode)
+    - **Replacement for A4988**
+    - Manual Vref/Stepper Current
+
+- Mode 2: Standalone STEP/DIR Driver with OTP pre-configuration
+    - OTP (One Time Programming)
+
+- Mode 3: STEP/DIR Driver with Full Diagnostics and Control
+    - **pin PDN_UART is connected to the CPU UART interface**
+
+## Set up as Mode 1
+
+### Mode select
+
+![](../images/stepper/mode_select.jpg){width=400}  
+
+- Mode 1: no jumber (default)
+
+### Stepper Motor
+
+![](../images/stepper/42SHD4002-24B.jpg)  
+[42SHD4002-24B](https://akizukidenshi.com/catalog/g/gP-14604/)|[datasheet](https://akizukidenshi.com/download/ds/fudeelec/42shd4002-24b.pdf)  
+![](../images/stepper/42SHD_spec.png){width=500}  
+![](../images/stepper/42SHD_wire.png){width=500}
+
+- Rated voltage: 12V
+- Rated current: 0.55A
+
+###  Vref formula
+#### RMS Current
+
+- Root Mean Square ([二乗平均平方根](https://ja.wikipedia.org/wiki/%E4%BA%8C%E4%B9%97%E5%B9%B3%E5%9D%87%E5%B9%B3%E6%96%B9%E6%A0%B9))
+
+RMS Current = MAX CURRENT / 1.41  
+VREF = (RMS Current x 2.5)/1.77)
+
+value      |formula                  |42SHD4002-24B           |Safer use 90% of VREF
+--         |---                      |--                      |--
+RMS Current|MAX Current / 1.41       |0.55[A] / 1.41 = 0.39   | -
+VREF       |(RMS Current x 2.5)/1.77 |(0.39 x 2.5)/1.77 = 0.55|0.55 x 0.9 = 0.495[V]  
+
+
+![](../images/stepper/vref_hole.jpg){width=300}
+![](../images/stepper/vref_screw.jpg){width=300}
+
+
+### Arduino
+
+#### Library
+
+New: [TMCStepper](https://github.com/teemuatlut/TMCStepper)  
+Old: [TMC2208Stepper](https://github.com/teemuatlut/TMC2208Stepper)  
+
+Sketch -> Include Library -> Library Manager -> Search "tmc"   -> install both libraries  
+![](../images/stepper/arduino_tmc2208_lib.png){width=400}
+
+#### sample Sketch
+
+File -> Examples ->  TMC2208Stepper -> TMC2208_Simple
+
+```
+// Author Teemu Mäntykallio, 2017-04-07
+
+// Define pins
+#define EN_PIN    38  // LOW: Driver enabled. HIGH: Driver disabled
+#define STEP_PIN  54  // Step on rising edge
+
+#include <TMC2208Stepper.h>                       // Include library
+TMC2208Stepper driver = TMC2208Stepper(&Serial1);  // Create driver and use
+                                                  // HardwareSerial0 for communication
+
+void setup() {
+  Serial.begin(9600);
+  Serial.println("Start...");
+  Serial1.begin(115200);        // Start hardware serial 1
+  driver.push();                // Reset registers
+
+  // Prepare pins
+  pinMode(EN_PIN, OUTPUT);
+  pinMode(STEP_PIN, OUTPUT);
+  digitalWrite(EN_PIN, HIGH);   // Disable driver in hardware
+
+  driver.pdn_disable(true);     // Use PDN/UART pin for communication
+  driver.I_scale_analog(false); // Use internal voltage reference
+  driver.rms_current(500);      // Set driver current 500mA
+  driver.toff(2);               // Enable driver in software
+
+  digitalWrite(EN_PIN, LOW);    // Enable driver in hardware
+
+  uint32_t data = 0;
+  Serial.print("DRV_STATUS = 0x");
+  driver.DRV_STATUS(&data);
+  Serial.println(data, HEX);
+}
+
+void loop() {
+  digitalWrite(STEP_PIN, !digitalRead(STEP_PIN));
+  delayMicroseconds(100);
+}
+```