Craig Evans
/
ELEC2645_UpDown_Counter_2021
Up Down Counter using FSM
Revision 0:7c0953072ecb, committed 2020-12-10
- Comitter:
- eencae
- Date:
- Thu Dec 10 13:42:11 2020 +0000
- Commit message:
- Initial Commit
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/.gitignore Thu Dec 10 13:42:11 2020 +0000 @@ -0,0 +1,4 @@ +.build +.mbed +projectfiles +*.py*
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/CONTRIBUTING.md Thu Dec 10 13:42:11 2020 +0000 @@ -0,0 +1,5 @@ +# Contributing to Mbed OS + +Mbed OS is an open-source, device software platform for the Internet of Things. Contributions are an important part of the platform, and our goal is to make it as simple as possible to become a contributor. + +To encourage productive collaboration, as well as robust, consistent and maintainable code, we have a set of guidelines for [contributing to Mbed OS](https://os.mbed.com/docs/mbed-os/latest/contributing/index.html).
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/README.md Thu Dec 10 13:42:11 2020 +0000 @@ -0,0 +1,64 @@ +![](./resources/official_armmbed_example_badge.png) +# Blinky Mbed OS example + +The example project is part of the [Arm Mbed OS Official Examples](https://os.mbed.com/code/) and is the [getting started example for Mbed OS](https://os.mbed.com/docs/mbed-os/v5.14/quick-start/index.html). It contains an application that repeatedly blinks an LED on supported [Mbed boards](https://os.mbed.com/platforms/). + +You can build the project with all supported [Mbed OS build tools](https://os.mbed.com/docs/mbed-os/latest/tools/index.html). However, this example project specifically refers to the command-line interface tool [Arm Mbed CLI](https://github.com/ARMmbed/mbed-cli#installing-mbed-cli). +(Note: To see a rendered example you can import into the Arm Online Compiler, please see our [import quick start](https://os.mbed.com/docs/mbed-os/latest/quick-start/online-with-the-online-compiler.html#importing-the-code).) + +1. [Install Mbed CLI](https://os.mbed.com/docs/mbed-os/latest/quick-start/offline-with-mbed-cli.html). + +1. Clone this repository on your system, and change the current directory to where the project was cloned: + + ```bash + $ git clone git@github.com:armmbed/mbed-os-example-blinky && cd mbed-os-example-blinky + ``` + + Alternatively, you can download the example project with Arm Mbed CLI using the `import` subcommand: + + ```bash + $ mbed import mbed-os-example-blinky && cd mbed-os-example-blinky + ``` + + +## Application functionality + +The `main()` function is the single thread in the application. It toggles the state of a digital output connected to an LED on the board. + +## Building and running + +1. Connect a USB cable between the USB port on the board and the host computer. +2. <a name="build_cmd"></a> Run the following command to build the example project and program the microcontroller flash memory: + ```bash + $ mbed compile -m <TARGET> -t <TOOLCHAIN> --flash + ``` +The binary is located at `./BUILD/<TARGET>/<TOOLCHAIN>/mbed-os-example-blinky.bin`. + +Alternatively, you can manually copy the binary to the board, which you mount on the host computer over USB. + +Depending on the target, you can build the example project with the `GCC_ARM`, `ARM` or `IAR` toolchain. After installing Arm Mbed CLI, run the command below to determine which toolchain supports your target: + +```bash +$ mbed compile -S +``` + +## Expected output +The LED on your target turns on and off every 500 milliseconds. + + +## Troubleshooting +If you have problems, you can review the [documentation](https://os.mbed.com/docs/latest/tutorials/debugging.html) for suggestions on what could be wrong and how to fix it. + +## Related Links + +* [Mbed OS Stats API](https://os.mbed.com/docs/latest/apis/mbed-statistics.html). +* [Mbed OS Configuration](https://os.mbed.com/docs/latest/reference/configuration.html). +* [Mbed OS Serial Communication](https://os.mbed.com/docs/latest/tutorials/serial-communication.html). +* [Mbed OS bare metal](https://os.mbed.com/docs/mbed-os/latest/reference/mbed-os-bare-metal.html). +* [Mbed boards](https://os.mbed.com/platforms/). + +### License and contributions + +The software is provided under Apache-2.0 license. Contributions to this project are accepted under the same license. Please see contributing.md for more info. + +This project contains code from other projects. The original license text is included in those source files. They must comply with our license guide.
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/main.cpp Thu Dec 10 13:42:11 2020 +0000 @@ -0,0 +1,126 @@ +/* + +2645_FSM_UpDown_Counter + +Sample code from ELEC2645 + +Demonstrates how to implement a simple FSM up/down counter + +(c) Craig A. Evans, University of Leeds, Jan 2016 +Updated Jan 2020 +Updated Dec 2020 + +*/ + +#include "mbed.h" +#include "platform/mbed_thread.h" + +// defines directions as 0/1. Note UPPERCASE +#define UP 0 +#define DOWN 1 + +// create a bus for writing to the output (LEDs) at once +BusOut output(LED4,LED3,LED2,LED1); +// Button A on board +InterruptIn buttonA(p29); + +// array of states in the FSM, each element is the output of the counter +// set the output in binary to make it easier, 1 is LED on, 0 is LED off +int g_fsm[4] = {0b0001,0b0010,0b0100,0b1000}; + +// flag - must be volatile as changes within ISR +// g_ prefix makes it easier to distinguish it as global +volatile int g_buttonA_flag = 0; + +// Button A interrupt service routine +void buttonA_isr(); + +int main() +{ + // Button A has a pull-down resistor, so the pin will be at 0 V by default + // and rise to 3.3 V when pressed. We therefore need to look for a rising edge + // on the pin to fire the interrupt + buttonA.rise(&buttonA_isr); + // since Button A has an external pull-down, we should disable to internal pull-down + // resistor that is enabled by default using InterruptIn + buttonA.mode(PullNone); + + // set inital state + int state = 0; + // set initial direction + int direction = UP; + + while(1) { // loop forever + + // check if flag i.e. interrupt has occured + if (g_buttonA_flag) { + g_buttonA_flag = 0; // if it has, clear the flag + + // swap direction when button has been pressed + // (could just use ! but want this to be explicit to aid understanding) + if (direction == UP) { + direction = DOWN; + } else { + direction = UP; + } + } + + output = g_fsm[state]; // output current state + + // check which state we are in and see which the next state should be next depending on direction + switch(state) { + case 0: + switch(direction) { + case UP: + state = 1; + break; + case DOWN: + state = 3; + break; + } + break; + case 1: + switch(direction) { + case UP: + state = 2; + break; + case DOWN: + state = 0; + break; + } + break; + case 2: + switch(direction) { + case UP: + state = 3; + break; + case DOWN: + state = 1; + break; + } + break; + case 3: + switch(direction) { + case UP: + state = 0; + break; + case DOWN: + state = 2; + break; + } + break; + default: // default case + error("Invalid state!"); //invalid state - call error routine + state = 0; + break; + } + + thread_sleep_for(500); + } +} + +// Button A event-triggered interrupt +void buttonA_isr() +{ + g_buttonA_flag = 1; // set flag in ISR +} \ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed-os.lib Thu Dec 10 13:42:11 2020 +0000 @@ -0,0 +1,1 @@ +https://github.com/ARMmbed/mbed-os/#cf4f12a123c05fcae83fc56d76442015cb8a39e9
Binary file resources/official_armmbed_example_badge.png has changed