README.md

# EZ-PD™ PMG1 MCU: Software UART transmit

This code example demonstrates UART transmit (TX) operation using software (SW) bit-banging technique on PMG1 devices. This application uses a serial terminal to transmit the data. Any GPIO pin can be configured as a transmit (TX) pin to send data using this code example.

[View this README on GitHub.](https://github.com/Infineon/mtb-example-pmg1-sw-uart-tx)

[Provide feedback on this code example.](https://cypress.co1.qualtrics.com/jfe/form/SV_1NTns53sK2yiljn?Q_EED=eyJVbmlxdWUgRG9jIElkIjoiQ0UyMzgxMzkiLCJTcGVjIE51bWJlciI6IjAwMi0zODEzOSIsIkRvYyBUaXRsZSI6IkVaLVBEJnRyYWRlOyBQTUcxIE1DVTogU29mdHdhcmUgVUFSVCB0cmFuc21pdCIsInJpZCI6Im1hbmFzYSIsIkRvYyB2ZXJzaW9uIjoiMS4wLjAiLCJEb2MgTGFuZ3VhZ2UiOiJFbmdsaXNoIiwiRG9jIERpdmlzaW9uIjoiTUNEIiwiRG9jIEJVIjoiV0lSRUQiLCJEb2MgRmFtaWx5IjoiVFlQRS1DIn0=)

## Requirements

- [ModusToolbox™](https://www.infineon.com/modustoolbox) v3.1 or later (tested with v3.1)
- Board support package (BSP) minimum required version: 3.1.0
- Programming language: C
- Associated parts: All [EZ-PD™ PMG1 MCU](https://www.infineon.com/PMG1) parts

## Supported toolchains (make variable 'TOOLCHAIN')

- GNU Arm® Embedded Compiler v11.3.1 (`GCC_ARM`) – Default value of `TOOLCHAIN`
- Arm® Compiler v6.16 (`ARM`)
- IAR C/C++ Compiler v9.30.1 (`IAR`)

## Supported kits (make variable 'TARGET')

- [EZ-PD™ PMG1-S0 Prototyping Kit](https://www.infineon.com/CY7110) (`PMG1-CY7110`) – Default value of `TARGET`
- [EZ-PD™ PMG1-S1 Prototyping Kit](https://www.infineon.com/CY7111) (`PMG1-CY7111`)
- [EZ-PD™ PMG1-S2 Prototyping Kit](https://www.infineon.com/CY7112) (`PMG1-CY7112`)
- [EZ-PD™ PMG1-S3 Prototyping Kit](https://www.infineon.com/CY7113) (`PMG1-CY7113`)

## Hardware setup

1. See the kit user guide to ensure that the board is configured correctly.

2. Connect the transmit (TX) pin from the PMG1 kit to J3.8 on KitProg3 to establish a transmit connection between KitProg3 and the PMG1 device.

**Table 1. GPIO configured as transmit (TX) pin**

 Resource  | Alias/object 
---------  | ------------  
PMG1-S0    | J7.12 / P1[1] 
PMG1-S1    | J7.12 / P1[3] 
PMG1-S2    | J7.4  / P2[4] 
PMG1-S3    | J6.17 / P5[2] 

## Software setup

See the [ModusToolbox™ tools package installation guide](https://www.infineon.com/ModusToolboxInstallguide) for information about installing and configuring the tools package.
Install a terminal emulator if you don't have one. Instructions in this document use [Tera Term](https://teratermproject.github.io/index-en.html).

This example requires no additional software or tools.

## Using the code example

### Create the project

The ModusToolbox™ tools package provides the Project Creator as both a GUI tool and a command line tool.

<details><summary><b>Use Project Creator GUI</b></summary>

1. Open the Project Creator GUI tool.

   There are several ways to do this, including launching it from the dashboard or from inside the Eclipse IDE. For more details, see the [Project Creator user guide](https://www.infineon.com/ModusToolboxProjectCreator) (locally available at *{ModusToolbox&trade; install directory}/tools_{version}/project-creator/docs/project-creator.pdf*).

2. On the **Choose Board Support Package (BSP)** page, select a kit supported by this code example. See [Supported kits](#supported-kits-make-variable-target).

   > **Note:** To use this code example for a kit not listed here, you may need to update the source files. If the kit does not have the required resources, the application may not work.

3. On the **Select Application** page:

   a. Select the **Applications(s) Root Path** and the **Target IDE**.

   > **Note:** Depending on how you open the Project Creator tool, these fields may be pre-selected for you.

   b.	Select this code example from the list by enabling its check box.

   > **Note:** You can narrow the list of displayed examples by typing in the filter box.

   c. (Optional) Change the suggested **New Application Name** and **New BSP Name**.

   d. Click **Create** to complete the application creation process.

</details>

<details><summary><b>Use Project Creator CLI</b></summary>

The 'project-creator-cli' tool can be used to create applications from a CLI terminal or from within batch files or shell scripts. This tool is available in the *{ModusToolbox&trade; install directory}/tools_{version}/project-creator/* directory.

Use a CLI terminal to invoke the 'project-creator-cli' tool. On Windows, use the command-line 'modus-shell' program provided in the ModusToolbox&trade; installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox&trade; tools. You can access it by typing 'modus-shell' in the search box in the Windows menu. In Linux and macOS, you can use any terminal application.

The following example clones the "[UART Bit Banging](https://github.com/Infineon/mtb-example-pmg1-sw-tx-uart)" application with the desired name "MyUARTBitBanging" configured for the *PMG1-CY7110* BSP into the specified working directory, *C:/mtb_projects*:

   ```
   project-creator-cli --board-id PMG1-CY7110 --app-id mtb-example-pmg1-sw-tx-uart --user-app-name MyUARTBitBanging --target-dir "C:/mtb_projects"
   ```

> **Note:** The project-creator-cli tool uses the `git clone` and `make getlibs` commands to fetch the repository and import the required libraries. For details, see the "Project creator tools" section of the [ModusToolbox&trade; user guide](https://www.infineon.com/ModusToolboxUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mtb_user_guide.pdf*).

To work with a different supported kit later, use the [Library Manager](https://www.infineon.com/ModusToolboxLibraryManager) to choose the BSP for the supported kit. You can invoke the Library Manager GUI tool from the terminal using the `make library-manager` command or use the Library Manager CLI tool "library-manager-cli" to change the BSP.

The 'project-creator-cli' tool has the following arguments:

Argument | Description | Required/optional
---------|-------------|-----------
`--board-id` | Defined in the <id> field of the [BSP](https://github.com/Infineon?q=bsp-manifest&type=&language=&sort=) manifest | Required
`--app-id`   | Defined in the <id> field of the [CE](https://github.com/Infineon?q=ce-manifest&type=&language=&sort=) manifest | Required
`--target-dir`| Specify the directory in which the application is to be created if you prefer not to use the default current working directory | Optional
`--user-app-name`| Specify the name of the application if you prefer to have a name other than the example's default name | Optional

<br>

The following example adds the PMG1-CY7110 BSP to the already created application and makes it the active BSP for the application:

   ```
   library-manager-cli --project "C:/mtb_projects/MyUARTBitBanging" --add-bsp-name PMG1-CY7110 --add-bsp-version "latest-v3.X" --add-bsp-location "local"

   library-manager-cli --project "C:/mtb_projects/MyUARTBitBanging" --set-active-bsp APP_PMG1-CY7110
   ```

</details>


### Open the project

After the project has been created, you can open it in your preferred development environment.

<details><summary><b>Eclipse IDE</b></summary>

If you opened the Project Creator tool from the included Eclipse IDE, the project will open in Eclipse automatically.

For more details, see the [Eclipse IDE for ModusToolbox&trade; user guide](https://www.infineon.com/MTBEclipseIDEUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mt_ide_user_guide.pdf*).

</details>

<details><summary><b>Visual Studio (VS) Code</b></summary>

Launch VS Code manually, and then open the generated *{project-name}.code-workspace* file located in the project directory.

For more details, see the [Visual Studio Code for ModusToolbox&trade; user guide](https://www.infineon.com/MTBVSCodeUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mt_vscode_user_guide.pdf*).

</details>

<details><summary><b>Keil µVision</b></summary>

Double-click the generated *{project-name}.cprj* file to launch the Keil µVision IDE.

For more details, see the [Keil µVision for ModusToolbox&trade; user guide](https://www.infineon.com/MTBuVisionUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mt_uvision_user_guide.pdf*).

</details>

<details><summary><b>IAR Embedded Workbench</b></summary>

Open IAR Embedded Workbench manually, and create a new project. Then select the generated *{project-name}.ipcf* file located in the project directory.

For more details, see the [IAR Embedded Workbench for ModusToolbox&trade; user guide](https://www.infineon.com/MTBIARUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mt_iar_user_guide.pdf*).

</details>

<details><summary><b>Command line</b></summary>

If you prefer to use the CLI, open the appropriate terminal, and navigate to the project directory. On Windows, use the command-line 'modus-shell' program; on Linux and macOS, you can use any terminal application. From there, you can run various `make` commands.

For more details, see the [ModusToolbox&trade; tools package user guide](https://www.infineon.com/ModusToolboxUserGuide) (locally available at *{ModusToolbox&trade; install directory}/docs_{version}/mtb_user_guide.pdf*).

</details>

## Operation

1. Ensure that the steps listed in the [Hardware setup](#hardware-setup) section are complete.

2. Ensure that the jumper shunt on the power selection jumper (J5) is placed at positions 2-3 to enable programming.

3. Connect the board to your PC using the USB cable through the KitProg3 USB connector. This cable is used for programming the EZ-PD&trade; PMG1 device and as a USB-to-UART bridge to the PC during operation.

4. Program the board using one of the following:

   <details><summary><b>Using Eclipse IDE</b></summary>

      1. Select the application project in the Project Explorer.

      2. In the **Quick Panel**, scroll down, and click **\<Application Name> Program (KitProg3_MiniProg4)**.
   </details>

   <details><summary><b>Using CLI</b></summary>

     From the terminal, execute the `make program` command to build and program the application using the default toolchain to the default target. The default toolchain is specified in the application's Makefile but you can override this value manually:
      ```
      make program TOOLCHAIN=<toolchain>
      ```

      Example:
      ```
      make program TOOLCHAIN=GCC_ARM
      ```
   </details>

5. After programming the kit, disconnect the USB cable, and change the position on the power selection jumper (J5) to 1-2 to power the kit through the USB Power Delivery (PD) port.

6. Connect the USB cable back to the KitProg3 USB connector and open a terminal program, and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud rate.

7. Connect the USB PD port to a USB-C power adapter or to your PC using a USB Type-C cable to power the kit.

8. The application starts automatically. The result is displayed on the terminal, as shown in **Figure 1**.

**Figure 1. Sample output**

<img src = "images/output.png" width = "600"/>


## Debugging

You can debug the example to step through the code.

<details><summary><b>In Eclipse IDE</b></summary>

In the IDE, use the **\<Application name> Debug (KitProg3_MiniProg4)** configuration in the **Quick Panel**.

Ensure that the board is connected to your PC using the USB cables through both the KitProg3 USB connector as well as the USB PD port, with the jumper shunt on the power selection jumper (J5) placed at position 1-2.

</details>
<details><summary><b>In other IDEs</b></summary>

Follow the instructions in your preferred IDE.
</details>

## Design and implementation

This example demonstrates how a GPIO pin can be configured as a transmit (TX) pin to perform UART transmit functionality using a software (SW) bit-banging technique. The UART data is transmitted asynchronously and there is no clock signal to synchronize the output. To begin the transfer of data, pull the transmitting UART line from high to low. To achieve this, write a logic '0' on to the GPIO pin and then apply a delay. 

After the start bit, data transmission takes place. The data is transmitted in 8-bit word, with the least significant bit (LSB) sent first and the most significant bit (MSB) sent last. The value of each bit is written on to the GPIO pin, followed by a delay. Once the data transmission is complete, the program checks for a parity bit. 

If the parity bit is odd, the application checks for the number of 1s in the data byte. If the result is odd, the parity bit is set to '0'; otherwise, it is set to '1'. The value of the parity bit is then written on to the GPIO pin, followed by a delay. If the parity bit is even, the application checks for the number of 1s in the data byte. If the result is even, the parity bit is set to '0'; otherwise, it is set to '1'. If the parity is set as none, then no parity bit is required. 

The UART transmission ends with a stop bit, which is set to logic 1. This is achieved by writing a logic '1' on to the GPIO pin, followed by a delay. 

The default baud rate is set to 115200 bps, with one stop bit and no parity. However, these values can be altered. 
If a framing error is encountered, it can be corrected by subtracting the delay with a certain number that corrects the framing error for a particular baud rate. For more information, see the comment above the macro **Delay**.

> **Note:** If any interrupt occurs, the data transmission will break and a framing error will be seen on the UART terminal. 

**Figure 2. UART frame**

<img src = "images/frame_format_of_uart.png" width = "500"/>

Figure 3 and Figure 4 shows the Device Configurator settings for UART TX.

**Figure 3. Device Configurator**

<img src = "images/configurator1.png" width = "500"/>

**Figure 4. Device Configurator**

<img src = "images/configurator2.png" width = "500"/>

**Figure 5. Firmware flowchart**

<img src = "images/flowchart.png" width = "500"/>

### Compile-time configurations

The code example functionality can be customized through a set of compile-time parameters that can be changed in the *uart_bit_banging.h* file.

Macro name  | Description   | Allowed values 
:-------  | :------------  | :------------ 
BAUD_RATE (uart_bit_banging.h) | Baud rate assigned | Supported baud rate is from 1200 bps to 115200 bps. 
DELAY (uart_bit_banging.h) | Delay applied for any baud rate | Subtract or add a delay in this macro to adjust the UART baud rate timing. This parameter needs adjusting with change in system clock, compiler, optimizations or sometimes change in baud rate. 
MAX_LENGTH (uart_bit_banging.h) | Maximum length of the string | Change this value to increase string length.  

<br>

### Resources and settings

**Table 3. Application resources**

 Resource  | Alias/object   | Purpose 
 :--------   | :-------------   | :------------
 GPIO (BSP) | TX | User transmit (TX) pin to send data

<br>


## Related resources

Resources | Links
-----------|----------------------------------
Application notes |[AN232553](https://www.infineon.com/AN232553) – Getting started with EZ-PD&trade; PMG1 MCU on ModusToolbox&trade; <br> [AN232565](https://www.infineon.com/an232565) – EZ-PD&trade; PMG1 hardware design guidelines and checklist
Code examples  | [Using ModusToolbox&trade;](https://github.com/Infineon/Code-Examples-for-ModusToolbox-Software) on GitHub
Device documentation | [EZ-PD&trade; PMG1 MCU datasheets](https://www.infineon.com/PMG1DS)
Development kits | Select your kits from the [Evaluation board finder](https://www.infineon.com/cms/en/design-support/finder-selection-tools/product-finder/evaluation-board) page.
Libraries on GitHub | [mtb-pdl-cat2](https://github.com/Infineon/mtb-pdl-cat2) – Peripheral Driver Library (PDL) and docs
Tools  | [ModusToolbox&trade;](https://www.infineon.com/modustoolbox) – ModusToolbox&trade; software is a collection of easy-to-use libraries and tools enabling rapid development with Infineon MCUs for applications ranging from wireless and cloud-connected systems, edge AI/ML, embedded sense and control, to wired USB connectivity using AIROC&trade; Wi-Fi and Bluetooth&reg; connectivity devices, XMC&trade; Industrial MCUs, and EZ-USB&trade;/EZ-PD&trade; wired connectivity controllers. ModusToolbox&trade; incorporates a comprehensive set of BSPs, HAL, libraries, configuration tools, and provides support for industry-standard IDEs to fast-track your embedded application development.

<br>

## Other resources

Infineon provides a wealth of data at [www.infineon.com](https://www.infineon.com) to help you select the right device, and quickly and effectively integrate it into your design.

## Document history

Document title: *CE238139* - *EZ-PD&trade;  PMG1 MCU: Software UART transmit*

 Version | Description of change 
 ------- | --------------------- 
 1.0.0   | New code example   

<br>

All referenced product or service names and trademarks are the property of their respective owners.

The Bluetooth&reg; word mark and logos are registered trademarks owned by Bluetooth SIG, Inc., and any use of such marks by Infineon is under license.


---------------------------------------------------------

© Cypress Semiconductor Corporation, 2024. This document is the property of Cypress Semiconductor Corporation, an Infineon Technologies company, and its affiliates ("Cypress").  This document, including any software or firmware included or referenced in this document ("Software"), is owned by Cypress under the intellectual property laws and treaties of the United States and other countries worldwide.  Cypress reserves all rights under such laws and treaties and does not, except as specifically stated in this paragraph, grant any license under its patents, copyrights, trademarks, or other intellectual property rights.  If the Software is not accompanied by a license agreement and you do not otherwise have a written agreement with Cypress governing the use of the Software, then Cypress hereby grants you a personal, non-exclusive, nontransferable license (without the right to sublicense) (1) under its copyright rights in the Software (a) for Software provided in source code form, to modify and reproduce the Software solely for use with Cypress hardware products, only internally within your organization, and (b) to distribute the Software in binary code form externally to end users (either directly or indirectly through resellers and distributors), solely for use on Cypress hardware product units, and (2) under those claims of Cypress's patents that are infringed by the Software (as provided by Cypress, unmodified) to make, use, distribute, and import the Software solely for use with Cypress hardware products.  Any other use, reproduction, modification, translation, or compilation of the Software is prohibited.
<br>
TO THE EXTENT PERMITTED BY APPLICABLE LAW, CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS DOCUMENT OR ANY SOFTWARE OR ACCOMPANYING HARDWARE, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  No computing device can be absolutely secure.  Therefore, despite security measures implemented in Cypress hardware or software products, Cypress shall have no liability arising out of any security breach, such as unauthorized access to or use of a Cypress product. CYPRESS DOES NOT REPRESENT, WARRANT, OR GUARANTEE THAT CYPRESS PRODUCTS, OR SYSTEMS CREATED USING CYPRESS PRODUCTS, WILL BE FREE FROM CORRUPTION, ATTACK, VIRUSES, INTERFERENCE, HACKING, DATA LOSS OR THEFT, OR OTHER SECURITY INTRUSION (collectively, "Security Breach").  Cypress disclaims any liability relating to any Security Breach, and you shall and hereby do release Cypress from any claim, damage, or other liability arising from any Security Breach.  In addition, the products described in these materials may contain design defects or errors known as errata which may cause the product to deviate from published specifications. To the extent permitted by applicable law, Cypress reserves the right to make changes to this document without further notice. Cypress does not assume any liability arising out of the application or use of any product or circuit described in this document. Any information provided in this document, including any sample design information or programming code, is provided only for reference purposes.  It is the responsibility of the user of this document to properly design, program, and test the functionality and safety of any application made of this information and any resulting product.  "High-Risk Device" means any device or system whose failure could cause personal injury, death, or property damage.  Examples of High-Risk Devices are weapons, nuclear installations, surgical implants, and other medical devices.  "Critical Component" means any component of a High-Risk Device whose failure to perform can be reasonably expected to cause, directly or indirectly, the failure of the High-Risk Device, or to affect its safety or effectiveness.  Cypress is not liable, in whole or in part, and you shall and hereby do release Cypress from any claim, damage, or other liability arising from any use of a Cypress product as a Critical Component in a High-Risk Device. You shall indemnify and hold Cypress, including its affiliates, and its directors, officers, employees, agents, distributors, and assigns harmless from and against all claims, costs, damages, and expenses, arising out of any claim, including claims for product liability, personal injury or death, or property damage arising from any use of a Cypress product as a Critical Component in a High-Risk Device. Cypress products are not intended or authorized for use as a Critical Component in any High-Risk Device except to the limited extent that (i) Cypress's published data sheet for the product explicitly states Cypress has qualified the product for use in a specific High-Risk Device, or (ii) Cypress has given you advance written authorization to use the product as a Critical Component in the specific High-Risk Device and you have signed a separate indemnification agreement.
<br>
Cypress, the Cypress logo, and combinations thereof, ModusToolbox, PSoC, CAPSENSE, EZ-USB, F-RAM, and TRAVEO are trademarks or registered trademarks of Cypress or a subsidiary of Cypress in the United States or in other countries. For a more complete list of Cypress trademarks, visit [www.infineon.com](https://www.infineon.com) Other names and brands may be claimed as property of their respective owners.