Stm8s Tutorials 4c144l

STM8S Tutorials – #1 Tools As we progress in this tutorial series we will come across almost all the main features of this 8-Bit controller. In this tutorial series we will focus mainly on STM8S series which is a medium code density member of STM8 family. ST microelectronics provides rich tech and evaluation platforms for a quick start. Most easy way to start with STM8 microcontroller is to grab aSTM8S Discovery board which is a low cost development board with all the necessary features to kickstart application development using STM8 mcu.

STM8S Features 

STM8 Core based on Harvard Architecture.

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16MHz Operation w/ 3-stage Pipeline

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32 KByte Program Memory

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2 KByte RAM

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Internal RC Oscillator

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3, 16 Bit Timers, One Advance, Two Gen Purpose Timers

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1, 8 Bit Timer

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UART, SPI, I2C Blocks

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10 bit, 10 Channel ADC

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Single Wire Programming Interface (SWIM)

This series guides you to get started with your STM8S Discovery board. Subsequent posts on STM8S tutorial series will guide you on further programming and interfacing with this feature rich 8-Bit controller. This particular post lists the necessary hardware and software required to start application development.

Software Tools These are minimum possible software tools required to start with STM8 Controllers in Windows OS. Go to following pages to required installation file. 1.

STVD [ST Visual Develop IDE] – IDE for compilation, debugging and project management

2.

STVP [ST Visual Programmer] – Burner Software

3.

Cosmic C Compiler for STM8 MCU That’s it, that’s all you need to start application development using STM8S controller. Install these 3 software in your windows based computer. [PS - Development tools for Linux based machines will be updated soon]. Once all three software packages are installed, next step is to configure STVP and STVD to work with STM8S Discovery Board.

STVP Configuration To configure STVP to program STM8S105C6T6 controller on Discovery board go to Menu bar in STVP and choose Configure ->Configure ST Visual Programmer

Note configure settings in Image below…

STVP Configuration for STM8S Discovery Board

STVD Configuration STVD is a great tool, it is used for efficient project management, debugging and overall IDE for STM8 controllers, but STVD is not a C compiler, to develop application programs using C language we need a C compiler that understands the language of STM8S internals and does all the cross compilation for STM8S. Cosmic C compiler is one such compiler. Cosmic compiler’s size limited evaluation version is free for at the link given in software tools section of this post. Once both STVD and Cosmic compiler are installed in system it is necessary to link the path of cosmic C compiler with STVD. So that, STVD knows where to look at, when it need to compile any C file. Go to STVD-> Project->Settings Choose following options in General Tab of Project Settings

STM8S STVD Settings to link Cosmic C compiler with STVD Once configuration of STVP and STVD is done we are now ready to write our first firmware for STM8S105Cx MCU.

STM8 Tutorials – #2 Hello World Program Without much talks, lets create our first “Hello World” application for STM8S Discovery Board. As practiced in embedded world, this time also, LED blinking is our way to say Hello to STM8S world. STM8S Discovery has an on-board Green Colored LED connected to PD0. We will blink this led on and off with some delay in between.

STM8S Discovery LED connected to PD0

STEP 1: STVD Workspace/Project Creation Create a new STVD Workspace from File menu

Step -1 Create Workspace

Step -2 Project Name

Step -3 Project Toolchain selection as Cosmic STM8

Step -4 Choose STM8S105C6 as Target MCU

Step – 5 Review Project File Tree

STEP – 2 Adding STM8S Definition header stm8s.h

To compile any C project for STM8S can not be done without mapping definition into suitable names. This file is very important and it will be there in all most all the projects. It maps addresses with suitable names. For example GPIOA base is at 0×5000, this file has definition to map 0×5000 to a name as “GPIOA”.

Add stm8s.h file into your project

that stm8s.h has been added in your project

STEP – 3 Writing the Code 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

#include "stm8s.h" void myDelay(void); void myDelay() { int i,j; for(i=0;i<1000;i++) { for(j=0;j<100;j++); } } main() { GPIOD->DDR |= 0x01; // PD.0 as Output GPIOD->CR1 |= 0x01; // PD.0 as Push Pull Type Output while (1) { GPIOD->ODR |=1<<0; // PD.o = 1 myDelay(); GPIOD->ODR &= ~(1<<0); // PD.0 = 0

22 23 } 24 }

myDelay();

STEP – 4 Compile and Build the Project Compile and build the necessary machine files by pressing F7. If build process does not produce any errors, our code is successfully cross compiled and machine code is now ready to on mcu program memory.

STEP – 5 the code onto MCU Program Memory Now, open STVP and open .s19 file from the Debug folder inside project directory.

After opening the .s19 file, choose Program current tab from STVP Menu options.

STVD after successful device programming

STM8 Tutorials #3 – Handling Inputs This is 3rd tutorial in series of tutorials on STM8 microcontroller by ST Microelectronics. In this tutorial, we will learn, how to handle inputs on GPIO ports/pins of STM8S controller. We are considering only Polling method of reading inputs in this article, Interrupt method will be covered later. Reading input on any of the STM8S GPIO pin is very straight forward. Lets take this step by step.

Step – 1 Declare the GPIO Pin/Port as Input One has to declare any GPIO pin as input before any physical signal input can be read from that GPIO pin. To declare the GPIO pin as Input we again need to set proper bits in DDR of corresponding port. Table below shows different combinations of DDR, CR1 & CR2 s in order to set any GPIO either as Input or Output and to enable or disable Pull ups and Interrupts.

STM8S GPIO Modes In this experiment we are going to use GPIO as Input with Pull up but without Interrupts. So, for example if I want to use PE.7 as input with Pull up enabled and Interrupt disabled. I need to write corresponding bit (bit 7) in DDR of PORTE as ’0′.

1 1

GPIOE->DDR &= ~(1<<7); // Declare PE.7 as Input GPIOE->CR1 |= 1<<7; // PE.7 Pull Up Enabled

Now, once we have set PE.7 as Input with Internal Pull-Up, we are now ready to read the input logic status at PE.7 Pin.

Step -2 Read Pin status from IDR STM8S has ODR to write on output port and IDR to read from input port. IDR is a read-only 8-bit . Logical value at any bit of IDR of a port, reflects the actual logical status of that pin of that port. For example, if Pin 7 of IDR of GPIOE is ’0′, that means, PE.7, if configured as input is currently set to logic ’0′.

Step – 3 Schematic Figure below shows the connections that I’ve made to experiment with Inputs. Circuit has a tactile switch connected to PE.7 and 3 LEDs connected to PC.2, PC.4 and PC.6 respectively.

STM8S105_Input_GPIO_Tutorials_Schematic

Step -4 Code below is main() function for input handling program. Whenever the presses the switch at PE.7, the input pin goes low, the code has a software wait for switch debounce. As the presses the switch, it will glow all the LED for approximately 1 second otherwise the LEDs remain off forever.

STM8S_input_handling_code