19-06-2013, 11:36 AM
CP210X BAUD RATE SUPPORT
CP210X BAUD RATE.pdf (Size: 191.66 KB / Downloads: 37)
Introduction
This document is intended for developers creating
products based on the CP210x USB to UART Bridge
Controller. It details the device's default baud rates and
describes how to change this default behavior to
support new baud rates. This document includes some
example usage scenarios and advanced part
customizability. Most products will work perfectly with
the default device characteristics and do not need any
customization defined in this document. Tweaking these
options in a design that is already working can have
adverse effects on communication reliability or
throughput if used improperly.
Default Device Behavior
An application can request any baud rate. The CP210x
device will translate this baud rate into one of 32 fixed
UART baud rates. Table 1 lists all possible ranges for an
application requested baud rate and shows the
corresponding UART baud rate for that requested
range.
Baud Rate Aliasing
Baud rate aliasing refers to configuring a specific baud rate range to target a baud rate that is different from its
default baud rate. This feature is only available on CP2102/3 devices; refer to the device data sheet for support
information. The application-requested baud rate ranges are static and can never be changed. On the other hand,
the actual UART baud rate corresponding to a particular baud rate range is fully customizable. This customization
is done using a Windows Dynamic Link Library (DLL) named CP210xManufacturing.DLL. Using the functions
available in this API (GetBaudRateConfig() and SetBaudRateConfig()) the EEPROM settings can be changed
using the USB connection. For more information on this API and corresponding functions, refer to “AN144: CP210x
Device Customization Guide.” The CP210x Baud Rate Configuration utility uses this API and is an example
program that demonstrates how to use this functionality in the CP210xManufacturing.DLL.
CP210x Baud Rate Configuration Utility
The main window of the CP210x Baud Rate Configuration Utility (Figure 1) has a pulldown list at the top which
shows all of the connected CP210x devices; this is where the CP210x device to be programmed can be selected.
If a CP210x device is plugged in after the program has been started, click the Refresh button to obtain the most
recent list of connected CP210x devices. The large list box displays the current configuration. Below the current
configuration are the Get Configuration, Set Configuration, Restore to Default, and Export Configuration buttons.
The next sections will further explain how and when to use these buttons.
Customizing the Current Configuration of a Device
To change the current configuration, double click on the line that contains the baud rate range to be changed, and
a window will open that contains the desired and actual baud rates for that range (Figure 3). Enter the new baud
rate in the Desired Baud Rate field, and the Actual Baud Rate field will update to show the closest baud rate the
CP210x hardware can achieve. Normally these two numbers will not be exactly the same, but as long as the actual
baud rate is within ±3% of the desired baud rate, the communication channel will work correctly.