Craig Evans
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 @@ + +# 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