Adjustable LED blinking speed using STM8S
Contents
1. wy UM0833 Y User manual Adjustable LED blinking speed using STM8S DISCOVERY touch sensing key October 2009 Application overview The Discover software demonstrates the touch sensing feature of the STM8S DISCOVERY evaluation board It may also be used as starter code for developers who need to manage this touch sensing key within applications that require a user interface The STM8S DISCOVERY is delivered with this code already programmed in the STM8S105C6T6 microcontroller Flash memory Once the STM8S105C6T6 is powered up through a USB cable connected to the host PC the LED LD1 starts blinking slowly meaning that the programming has been completed successfully m Each time the TS1 key is pressed LD1 blinking speed increases m The third time TS1 is pressed LD1 is switched off m You can then restart a blinking cycle by pressing TS1 again The Discover demonstration software can available from the STM8S DISCOVERY web pages at http www st com mcu Reference documents m STM8S DISCOVERY evaluation board use manual UM0817 m Developing and debugging your STM8S DISCOVERY application code user manual UM0834 Doc ID 16489 Rev 1 1 11 www st com Contents UM0833 Contents 1 Application description 0 0 0c eee ee 4 1 1 Hardware required varanen edes pads Ned easeeeee ead a 4 1 2 Application schematics eeen eee eee 4 1 3 Application principle 2s icscssiceeaesetavns eee nnen edn2. library online help for details concerning these define statements Table 2 Touch Sensing library configuration Function define statement Value Comment MCU selection STM8S 1 i TIMACQ TIM3 Acquisition timer TIM3 base address TIMACQ CNTR_ADD 0x5328 Time base timer TIMTICK TIM4 LOADREF PORT ADDR GPIOC_BaseAdress Load I O Port PC4 selected LOADREF_ BIT 0x04 6 11 Doc ID 16489 Rev 1 ky UM0833 Software description Table 2 Touch Sensing library configuration continued Function define statement Value Comment SCKEY P1 KEY COUNT 1 Number of keys 1 SCKEY P1 PORT ADDR TT GPIOC_BaseAddress por Gee SCKEY P1 A 0x02 Pin 1 selected as Single channel key ne acquisition input SCKEY _P1 DRIVEN SHIELD MASK x Pin 3 for active shield 0 SCKEY P2 COUNT Key port P2 not used TAH 0 Key port P3 not used SCKEY_P3 COUNT Multichannel key NUMBER_OF_MULTI_CHANNEL_KEYS 0 Multichannel key feature disabled GPIOA ELECTRODES MASK GPIOB ELECTRODES MASK 0x00 GPIOC_ELECTRODES MASK 0x00 Ox0A Defines the electrode GPIOD ELECTRODES MASK 0x00 mask for each GPIO Electrode mask GPIOE ELECTRODES MASK 0x00 used 0x00 Mask must be set to 0x00 GPIOF ELECTRODES MASK 0x00 for unused GPIOs GPIOG_ELECTRODES_MASK 0x00 GPIOH ELECTRODES MASK 0x00 GPIOI_ELECTRODES MASK 2 2 Standard STM8S standard firmware library configuration The stm8s_conf h file of the STM8S standard firmware libr
3. nne 5 2 Software description 000 cece eee eee eee 6 2 1 Touch sensing library configuration neen 6 2 2 Standard STM8S standard firmware library configuration 7 2 3 Application software flowcharts oee 8 2 3 1 Main loop flowchart eeen 8 2 3 2 ExtraCode_StateMachine flowchart ee 9 3 REVISION history nnn nen a ee ee we me oa 10 2 11 Doc ID 16489 Rev 1 ky UM0833 List of figures List of figures Figure 1 Figure 2 Figure 3 Application schematics aen 4 Main application loop flowchart eee 8 ExtraCode_StateMachine flowchart neen 9 Doc ID 16489 Rev 1 3 11 Application description UM0833 1 Application description 1 1 Hardware required The following STM8S DISCOVERY on board resources are used e LED LDI Touch sensing key TS1 No additional hardware is required to make this application software run on the STM8S DISCOVERY kit 1 2 Application schematics Figure 1 shows the touch sensing key implementation principle based on the RC acquisition method For STM8S DISCOVERY implementation details refer to the board schematic provided in the STM8S DISCOVERY user manual UM0817 Resistor R4 is the main resistor used to adjust the electrode touch sensitivity Resistor R6 10 KO is optional It is used to reduce noise sensitivity As soon as a finger touches electrode TS1 the STM8S microcontroller detects the small variation in the RC network capacitance composed of R
4. 4 R6 and electrode capacitance Cx This is done by monitoring Cx charge discharge through PC1 acquisition I O For detailed information about RC acquisition principle for Touch Sensing applications refer to AN2927 Figure 1 Application schematics PC2 load I O ai17219 4 11 Doc ID 16489 Rev 1 ky UM0833 Application description 1 3 Application principle This application uses the timer TIM4 as a time base generator to control the blinking speed of the LED LD1 Each time the STM8S microcontroller detects a touch event on TS1 TIM4 time base is reprogrammed to change the blinking speed At application start up the timer time base is configured to 1 second and LD1 toggles slowly every second This configuration allows to check visually that the STM8S Flash memory was successfully programmed Each time a touch event is detected on the TS1 key LD1 blinking speed is increased according to the timer time base settings described in Table 7 At the third touch the LED is switched off You can then restart the blinking cycle Table 1 LED LD1 configuration TS1 state LD1 state Timer time base At start up LD1 toggles 1s 1st TS1 touch LD1 toggles 200 ms 2nd TS1 touch LD1 toggles 100 ms 3rd TS1 touch LD1 is switched off N A Doc ID 16489 Rev 1 5 11 Software description UM0833 2 Software description The application software uses both STM8 standard and tou
5. ary is used to configure the library by enabling the peripheral functions used by the application The following define statements must be present define CLK 1 enables the clock control CLK define _GPIO 1 enables the GPIOs 4 Doc ID 16489 Rev 1 7 11 Software description UM0833 2 3 2 3 1 Application software flowcharts This section gives an overview of the application software main loop as well as of the function that controls LD1 blinking speed Detailed information can be found in the STM8S DISCOVERY software user manual UM0834 Main loop flowchart Figure 2 shows the flowchart of the application software main loop Functions TSL Init and TSL Action in the API of the touch sensing library initialize the library and control the state machine that sequences the touch sensing management Figure 2 Main application loop flowchart Clock_Configuration age ents a Mate Configures HSE as system clock source gt Fmaster 16 MHz Configures port PDO as output push pull low GPIO_Configuration to drive LED LD1 ExtraC ode_Init StartTimer LD1 is switched Heinen Initializes memory API and struc in the Touch sensing Library meenen Initializes TS1 key state machine EN Starts timer TIM4 configured as timebase for LED toggling speed Inerements variable BlinkSpeed modulo 3 each time a touch event occurs on TS1 According to the value of BlinkSpeed makes the LED b
6. ch sensing firmware libraries to control general purpose functions plus touch sensing peripherals These functions and peripherals are the following Clock CLK The clock control enables and delivers the correct clock frequency to the CPU and peripherals It configures the HSI prescaler division factor from 8 to 1 e GPIOs They drive the MCU I Os to interface with external hardware They configure port PDO as output push pull low to drive the LED LD1 e TIM3 TIMS is a 16 bit timer with an 8 bit prescaler The touch sensing firmware library uses TIM3 for touch sensing acquisition TIMACQ See Table 2 for the corresponding define statement in the STM8S touch sensing library e TIM4 TIM4 is a basic 8 bit timer used as a generic time base TIMTICK This time base is used by the touch sensing firmware library to control the charge discharge cycles of the RC network resistor R4 plus TS1 electrode TIM4 is also used by the application to control LD1 blinking speed It is distinct from the acquisition timer TIM3 See Table 2 for the corresponding define statement in the STM8S touch sensing library 2 1 Touch sensing library configuration The STM8_TSL_RC_Configuration h file configures the touch sensing library Table 2 describes the main define statements required to configure the library for the STM8S DISCOVERY to control TS1 touch sensing key The other define statements should keep their default values Refer to the STM8S touch sensing
7. link at different rates or ExtraCode_StateMachine switches it off Main Touch sensing state machine TSL_Action performing the sequencing of all the actions concerning the touch key ai17220 8 11 4 Doc ID 16489 Rev 1 UM0833 Software description 2 3 2 ExtraCode_StateMachine flowchart Figure 3 shows the detailed flowchart of the ExtraCode StateMachine function The ExtraCode StateMachine function implements the algorithm that controls the LED blinking speed according to the number of times TS1 key is pressed LD1 blinking speed is controlled by the TIMTICK timer TIM4 This timer that is mainly used by the touch sensing firmware library to control the charge discharge timing of the RC network is already configured to generate a 100 ms time base An interrupt is asserted every 100 ms It sets a dedicated User flag 100ms flag to warn the application when the counter has reached the preprogrammed value The function Delay counts the number of times this flag has been set before making the LED toggle As a result the delay time can only be a multiple of 100 ms When a touch event is detected on TS1 the BlinkSpeed variable is incremented modulo 3 by the main routine see Figure 3 and the delay time is modified resulting in a change of the LED blinking frequency refer to Table 1 Figure 3 ExtraCode StateMachine flowchart Delay 1s A zen BlinkSpeed 1 Delay 200
8. ms Toggle LD1 BlinkSpeed 2 Delay 100 ms Toggle LD1 S BlinkSpeed 0 Write PDO to 1 Switch off LD1 ai17221 Doc ID 16489 Rev 1 9 11 Revision history UM0833 3 10 11 Revision history Table 3 Document revision history Date Revision Changes 29 Oct 2009 1 Intitial release Doc ID 16489 Rev 1 UM0833 Please Read Carefully Information in this document is provided solely in connection with ST products STMicroelectronics NV and its subsidiaries ST reserve the right to make changes corrections modifications or improvements to this document and the products and services described herein at any time without notice All ST products are sold pursuant to ST s terms and conditions of sale Purchasers are solely responsible for the choice selection and use of the ST products and services described herein and ST assumes no liability whatsoever relating to the choice selection or use of the ST products and services described herein No license express or implied by estoppel or otherwise to any intellectual property rights is granted under this document If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party p
9. onics All other names are the property of their respective owners 2009 STMicroelectronics All rights reserved STMicroelectronics group of companies Australia Belgium Brazil Canada China Czech Republic Finland France Germany Hong Kong India Israel Italy Japan Malaysia Malta Morocco Philippines Singapore Spain Sweden Switzerland United Kingdom United States of America www st com Y Doc ID 16489 Rev 1 11 11
10. roducts or services or any intellectual property contained therein UNLESS OTHERWISE SET FORTH IN ST S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY WITH RESPECT TO THE USE AND OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED WARRANTIES OF MERCHANTABILITY FITNESS FOR A PARTICULAR PURPOSE AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION OR INFRINGEMENT OF ANY PATENT COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZED ST REPRESENTATIVE ST PRODUCTS ARE NOT RECOMMENDED AUTHORIZED OR WARRANTED FOR USE IN MILITARY AIR CRAFT SPACE LIFE SAVING OR LIFE SUSTAINING APPLICATIONS NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY DEATH OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ST PRODUCTS WHICH ARE NOT SPECIFIED AS AUTOMOTIVE GRADE MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER S OWN RISK Resale of ST products with provisions different from the statements and or technical features set forth in this document shall immediately void any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever any liability of ST ST and the ST logo are trademarks or registered trademarks of ST in various countries Information in this document supersedes and replaces all information previously supplied The ST logo is a registered trademark of STMicroelectr
Download Pdf Manuals
Related Search