USBUART in PSoC® 3 / PSoC 5
CE60246
Project Name: USBUART_Example_Project
Programming Language: C
®
Software Version: PSoC Creator™ 1.0
Related Hardware: CY8CKIT-001
Prerequisites: USBUART_Lib
Author: Dan Sweet
Objective
®
CE60246 demonstrates the use of a custom developed USBUART component with PSoC 3 / PSoC 5.
Overview
The USBUART component uses a USB interface to emulate a COM port. This custom component is based on a
standard USB component, modified to enumerate and act as a CDC USB device. High-level communication
functions are available on the PSoC device side and the PC communicates through a standard terminal program.
This example project demonstrates a PSoC project using a USBUART component to echo any data sent to it from
a PC terminal.
Component List
Instance Name
Component Name
Version
Component Category
USBUART_1
USBUART
1.0
Custom
Comments
VID, PID, Device Release, Mfr String and Product
String are set
The USBUART component is the only component used in this example. To use this component in a project, a
dependency must be set pointing to the library project containing the USBUART component. The instructions for
adding this component to your own project are mentioned in the following section.
Importing a Custom Component in a Project
Follow these steps to add the USBUART component to a new project:
Right click on the project name in the Workspace Explorer and select Dependencies.
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Add a new User Dependency. Navigate to and select the USBUART_Component_Library.cyprj file provided with the
example project.
Ensure Components is selected and the Code check box is cleared.
Click OK and the USBUART component now appears in a new tab in the Component Catalog. It is now ready to be
placed on your schematic.
Top Design
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Component Configuration
USBUART
Note Each USB product must have a unique combination of Vendor ID (VID) and Product ID (PID). The default
values provided here are used as an example, but a unique VID (assigned by the USB Implementers Forum) and
PID must be used in a final product.
Design Wide Resources
Changes must be made in the Clocks tab in the design wide resources file (.cydwr) to use USB on the PSoC 3
device. The clocks can be configured by clicking Edit Clock in the Clocks tab. You must make the following
changes.
IMO: Select Osc 24.000 MHz.
PLL: Select Input from IMO and desired frequency as 48MHz.
ILO: Select 100 kHz.
USB: Enable and select IMOx2 – 48.000 MHz.
Master Clock: Select PLL_OUT– 48.000 MHz.
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Operation
This project echoes any data sent to it through the PC COM terminal. During initialization, global interrupts are
enabled and the USBUART component is started and enumerated. In the main loop, the receive buffer is checked
for data. If data exists, the data is read out of the buffer and written back to the PC. After writing data to the PC,
the PSoC must wait for the transmission to complete before continuing; otherwise, the PSoC may send new data
to the PC before it is ready. This code is shown in Code 1.
Code 1 USBUART Example Code
#include <device.h>
uint8 Count;
uint8 Buffer[128];
void main()
{
/* Initialization Code: */
CYGlobalIntEnable;
USBUART_1_Start(0, USBUART_1_3V_OPERATION);//!!NOTE!! Make sure this matches your board voltage!
while(!USBUART_1_bGetConfiguration());
USBUART_1_CDC_Init();
/* Main Loop: */
for(;;)
{
Count = USBUART_1_bGetRxCount();
if(Count != 0)
{
USBUART_1_ReadAll(Buffer);
USBUART_1_Write(Buffer, Count);
while(!USBUART_1_bTxIsReady()){}
}
}
/* Check for input data from PC */
/* Echo data back to PC */
/* Wait for Tx to finish */
}
Apart from the standard USBFS APIs, the following APIs are implemented for this component.
uint8 USBUART_bGetRxCount(void)
Description: Get the size of valid data in the receive buffer
Parameters: None
Return Value: uint8 : Returns the number of valid data bytes in the receive buffer
void USBUART_ReadAll (uint8 *pData)
Description: Reads all data from the receive buffer into pData.
Parameters: (uint8*) pData , the pointer to the array to which data the data from receive buffer will be loaded into.
Return Value: None
void USBUART_Write(uint *pData, uint8 bLength)
Description: Writes the data to the Tx buffer
Parameters:
uint* pData: the pointer to the array from which data will be loaded to the Tx buffer
uint8 bLength: The number of bytes that are written from array pData to the Tx buffer.
Return Value: None
uint8 USBUART_bTxIsReady(void)
Description: Checks to see if the device is ready to send data
Parameters: None
Return Value: uint8, If the device is not ready to transmit data, 0 is returned. Else, the Tx buffer size is returned.
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uint8 USBUART_CDC_Init(void)
Description: Initializes the component
Parameters: None
Return Value: uint8, this function returns 1.
Note this function was called USBUART_Init in previous versions of the component (distributed with code example
Rev *D and earlier).
Hardware Connections
You can use the default jumper settings of CY8CKIT-001 available in PSoC Development Kit Board Guide. This project
should be adaptable to work on almost any board with USB capabilities. Note this does not include the CY8CKIT-003
FirstTouch Starter Kit, which does not have a USB interface.
Jumper 8 may be changed to VBUS location, if you wish to power the board through USB.
Output
Build the project and program the chip.
Note The default device selection is PSoC 3 (CY8C3866AXI-040).To use this project with PSoC 5 family, do the following:
Go to Project Device Selector Select PSoC 5 device (CY8C5588AXI-060), build the project again and program the
PSoC 5 device as follows:
Plug the USB cable into the DVK and reset the board (SW4). When Windows prompts you with Found New Hardware
Wizard, direct the wizard to the
\USBUART_Example_Project\USBUART_Example_Project.cydsn\Generated_Source\PSoC 3 directory,
where the USBUART_CDC.inf file is located. This allows the device to enumerate correctly.
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Check to see which COM port the device is mapped to in the Device Manager.
Open a COM terminal (such as HyperTerminal) and select the appropriate port. The baud rate selected does not matter.
Ensure that the local echo is turned OFF.
When a connection is established, the PSoC returns any information typed in the terminal.
Related Application Notes and Example Projects
USB Peripheral Basics - AN57294
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PSoC 3 / PSoC 5 USB HID Fundamentals - AN57473
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PSoC 3 / PSoC 5 USB HID Intermediate - AN58726
®
USB Bulk Loopback With PSoC 3 - AN56718
®
USB Vendor Commands with PSoC 3 - AN56377
®
Interrupt Loopback - PSoC 3 / PSoC 5
®
Isochronous Transfers in PSoC 3 / PSoC 5
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Document History
®
Document Title: USBUART in PSoC 3 / PSoC 5
Document Number: 001-60246
Revision
ECN
Orig. of
Change
Submission
Date
Description of Change
**
2889259
DRSW
03/16/2010
New example project
*A
2930450
DRSW
05/10/2010
1. Fixed mistake in clock setting instructions and updated related screen
shot
2. Updated project to fix a warning message and mistake in component
datasheet.
3. Shortened some folder names and library project name.
*B
2959649
DRSW
06/23/2010
Updated project and document to support Beta 4.1 and PSoC 5.
*C
3013689
DRSW
08/23/2010
Updated software version.
*D
3119539
DRSW
01/21/2011
GCC compiler warnings are fixed and project rebuilt in FCS RC9.
Two copies of the project attached - one with ES2 as the default device,
one with ES3 as the default device. Otherwise, the projects are identical.
*E
3287514
DRSW
06/20/2011
Updated component to fix enumeration bug with 5 V operation that
occurred on a small number of USB hubs.
Updated project and example code to use new USBUART_CDC_Init API
Specified this example project does not work on the CY8CKIT-003
FirstTouch Starter Kit, which does not have a USB interface.
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