SILICON LABS CP2101 Interface Controller
Specifications
- Product Name: CP2102C USB to UART Bridge
- Max Baud Rate: 3Mbps
- Data Bits: 8
- Stop Bits: 1
- Parity Bit: Odd, Even, None
- Hardware Handshake: Yes
- Driver Support: Virtual COM Port Driver, USBXpress Driver
- Other Features: RS-232 Support, GPIOs, Break Signaling
Product Usage Instructions
Device Compatibility
- The CP2102C device is designed to replace existing single-interface CP210x USB-to-UART devices without the need for additional drivers. It is compatible with devices like CP2102, CP2102N, and CP2104 with minimal hardware changes.
Pin Compatibility
- The CP2102C is largely pin-compatible with most CP210x devices, except for the VBUS pin which requires connection to a voltage divider for proper operation. Refer to the table for specific replacements for different CP210x devices.
Installation Steps
- Connect the CP2102C device to the host computer using a USB cable.
- The default CDC driver provided by the Operating System will automatically recognize the CP2102C as a USB to UART bridge.
- No additional driver installation is required for basic functionality.
- If necessary, make minor hardware changes as per the specific device being replaced.
Overview
The CP2102C device is designed to act as a USB to UART bridge that works with the default CDC driver provided by the Operating System. This device can be used to re-place existing single-interface CP210x USB-to-UART devices without installing any drivers.
For some devices, such as the CP2102, CP2102N, and CP2104, the CP2102C is virtu-ally a drop in replacement. Apart from the addition of two resistors, no other hardware changes or software are required to use the CP2102C in existing designs. For other devices, slight package or feature differences may require minor changes to hardware. This application note describes in detail the steps required to integrate a CP2102C de-vice into a design in place of a previous CP210x device.
Devices covered by this application note are: CP2101, CP2102/9, CP2103, CP2104, and CP2102N. The multiple-interface devices, such as the CP2105 and CP2108, are not discussed.
KEY POINTS
- The CP2102C maintains a high degree of UART feature compatibility with most existing CP210x devices.
- Design will require minimal hardware changes when migrating to the CP2102C.
- The CP2102C provides a migration path for:
- CP2101
- CP2102/9
- CP2103
- CP2104
- CP2102N
Device Comparison
Feature Compatibility
The table below provides a full feature comparison table for all CP210x devices, including the CP2102C. In general, the CP2102C meets or exceeds the feature set of all previous CP210x devices.
Table 1.1. CP210x Family Features
| Feature | CP2101 | CP2102 | CP2109 | CP2103 | CP2104 | CP2102N | CP2102C |
| Re-programmable | X | X | X | X | |||
| One-time-programmable | X | X | |||||
| UART Features | |||||||
| Max Baud Rate | 921.6kbps | 921.6kbps | 921.6kbps | 921.6kbps | 921.6kbps | 3Mbps | 3Mbps |
| Data Bits: 8 | X | X | X | X | X | X | X |
| Data Bits: 5, 6, 7 | X | X | X | X | X | X | |
| Stop Bits: 1 | X | X | X | X | X | X | X |
| Stop Bits: 1.5, 2 | X | X | X | X | X | X | |
| Parity Bit: Odd, Even, None | X | X | X | X | X | X | X |
| Parity Bit: Mark, Space | X | X | X | X | X | X | |
| Hardware Handshake | X | X | X | X | X | X | X1 |
| X-ON/X-OFF Handshake | X | X | X | X | X | X | |
| Event Character Support | X | X | X | X | |||
| Line Break Transmission | X | X | X | X | X2 | ||
| Baud Rate Aliasing | X | X | X | ||||
| Driver Support | |||||||
| Virtual COM Port Driver | X | X | X | X | X | X | |
| USBXpress Driver | X | X | X | X | X | X | |
| Other Features | |||||||
| RS-232 Support | X | X | X | X | X | X | X |
| RS-485 Support | X | X | X | ||||
| GPIOs | None | None | None | 4 | 4 | 4-7 | None |
| Battery Charger Detect | X | ||||||
| Remote Wake-up | X | ||||||
| Clock Output | X | ||||||
Note
- Because the hardware handshake is default enabled, we recommend connecting CTS with a weak pull down resistor so that the device can still work normally if the pins are not fully connected (RTS, CTS).
- The CP2102C supports break signaling with an external 10 kOhm resistor between TXD and ground.
Pin Compatibility
With the exception of its VBUS pin, which must be connected to a voltage divider for proper operation, the CP2102C is largely pin-compatible with most CP210x devices. Below is a table of variants of the CP2102C that can be used to replace previous CP210x devices.
Table 1.2. CP2102C Replacements for CP210x Devices
| CP210x Device | Pin-Compatible Replacement |
| CP2101 | CP2102C-A01-GQFN28 |
| CP2102/9 | CP2102C-A01-GQFN28 |
| CP2103 | None (refer to for migration considerations) |
| CP2104 | CP2102C-A01-GQFN24 |
| CP2102N | CP2102C-A01-GQFN24 / CP2102C-A01-GQFN28 |
As the CP2102C datasheet notes, there are two relevant restrictions on the VBUS pin voltage in self-powered and bus-powered configurations. The first is the absolute maximum voltage allowed on the VBUS pin, which is defined as VIO + 2.5 V in Absolute
Maximum Ratings table. The second is the input high voltage (VIH) that is applied to VBUS when the device is connected to a bus, which is defined as VIO – 0.6 V in the table of GPIO specifications.
A resistor divider (or functionally-equivalent circuit) on VBUS, as shown in Figure 1.1 Bus-Powered Connection Diagram for USB Pins and Figure 1.2 Self-Powered Connection Diagram for USB Pins for bus- and self-powered operation, respectively, is required to meet these specifications and ensure reliable device operation. In this case, the current limitation of the resistor divider prevents high VBUS pin leakage current, even though the VIO + 2.5 V specification is not strictly met while the device is not powered.
Figure 1.1. Bus-Powered Connection Diagram for USB Pins
Figure 1.2. Self-Powered Connection Diagram for USB Pins
Device Migration
The following sections describe the migration considerations when transitioning from an existing CP210x device to a CP2102C device.
CP2101 to CP2102C
Hardware Compatibility
- The CP2102C-A01-GQFN28 is pin-compatible with the CP2101 with the addition of the voltage divider circuit shown in Figure 1.1 Bus-Powered Connection Diagram for USB Pins and Figure 1.2 Self-Powered Connection Diagram for USB Pins.
Software Compatibility
The CP2102C has a UART feature compatible with the CP2101. No software changes will be required when transitioning a CP2101 design to the CP2012C.
CP2102/9 to CP2102C
Hardware Compatibility
- The CP2102C-A01-GQFN28 is pin compatible with the CP2102/9 with the addition of the voltage divider circuit shown in Figure 1.1 Bus-Powered Connection Diagram for USB Pins and Figure 1.2 Self-Powered Connection Diagram for USB Pins.
- The CP2109 has an additional hardware requirement that the VPP pin (pin 18) should be connected to a capacitor to ground for in-system programming. This capacitor is not required on the CP2102C and can be safely omitted.
Software Compatibility
The CP2102C is compatible with the CP2102/9 with one exception:
- Baud Rate Aliasing
Baud Rate Aliasing is a feature that allows a device to use a pre-defined baud rate in place of a baud rate that is requested by the user. For example, a device using Baud Rate Aliasing can be programmed to use a baud rate of 45 bps whenever 300 bps is requested.
Baud Rate Aliasing is not supported on the CP2102C.
If Baud Rate Aliasing is used in a CP2102/9 design, the CP2102C is incompatible as a replacement.
CP2103 to CP2102C
Hardware Compatibility
The CP2102C does not have a pin-compatible variant that can replace the CP2103:
- The CP2103 QFN28 package has an additional VIO pin at pin 5 which shifts the function of the previous pins on the package clock-wise around the package by one pin compared to the CP2102C QFN28 package. This affects pins 1-5 and 22-28.
- Unlike the CP2103, the CP2102C does not support extra functionality on pins 16-19.
- All other pins remain in the same configuration.
If a separate VIO rail is required for a design, the smaller CP2102C QFN24 variant can be used. This variant has an identical function-ality set as the CP2103, but in the smaller QFN24 package.
Aside from this difference in pin-outs, no other hardware changes are required to migrate from the CP2103 to the CP2102C.
Software Compatibility
The CP2102C has a UART feature compatible with the CP2103 with one exception: Baud Rate Aliasing.
Baud Rate Aliasing is a feature that allows a device to use a pre-defined baud rate in place of a baud rate that is requested by the user. For example, a device using Baud Rate Aliasing can be programmed to use a baud rate of 45 bps whenever 300 bps is requested.
Baud Rate Aliasing is not supported on the CP2102C.
If Baud Rate Aliasing is used in a CP2103 design, the CP2102C is incompatible as a replacement.
CP2104 to CP2102C
Hardware Compatibility
The CP2102C-A01-GQFN24 is pin compatible with the CP2104 with the addition of the voltage divider circuit shown in Figure 1.1 Bus-Powered Connection Diagram for USB Pins and Figure 1.2 Self-Powered Connection Diagram for USB Pins.
No other hardware changes are required when transitioning a CP2104 design to the CP2102C. The CP2104 does require a capacitor between VPP (pin 16) and ground for in-system programming, but this pin is not connected on the CP2102C. Whether or not this capacitor is attached to this pin will have no effect on the CP2102C.
Software Compatibility
The CP2102C has a UART feature compatible with the CP2104. No software changes will be required when transitioning a CP2104 design to the CP2012C.
CP2102N to CP2102C
Hardware Compatibility
The CP2102C-A01-GQFN24 / CP2102C-A01-GQFN28 are pin compatible with the CP2102N-A02-GQFN24 / CP2102N-A02-GQFN28 with the addition of the voltage divider circuit shown in Figure 1.1 Bus-Powered Connection Diagram for USB Pins and Figure 1.2 Self-Powered Connection Diagram for USB Pins. No other hardware changes are required when transitioning a CP2102N design to the CP2102C.
Software Compatibility
The CP2102C has a UART feature compatible with the CP2102N. No software changes will be required when transitioning a CP2102N design to the CP2012C.
Disclaimer
Silicon Labs intends to provide customers with the latest, accurate, and in-depth documentation of all peripherals and modules available for system and software imple-menters using or intending to use the Silicon Labs products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each specific device, and “Typical” parameters provided can and do vary in different applications. Application examples described herein are for illustrative purposes only. Silicon Labs reserves the right to make changes without further notice to the product information, specifications, and descriptions herein, and does not give warranties as to the accuracy or completeness of the included information. Without prior notification, Silicon Labs may update product firmware during the manufacturing process for security or reliability reasons. Such changes will not alter the specifications or the performance of the product. Silicon Labs shall have no liability for the consequences of use of the infor-mation supplied in this document. This document does not imply or expressly grant any license to design or fabricate any integrated circuits. The products are not designed or authorized to be used within any FDA Class III devices, applications for which FDA premarket approval is required or Life Support Systems without the specific written consent of Silicon Labs. A “Life Support System” is any product or system intended to support or sustain life and/or health, which, if it fails, can be reasonably expected to result in significant personal injury or death. Silicon Labs products are not designed or authorized for military applications. Silicon Labs products shall under no circumstances be used in weapons of mass destruction including (but not limited to) nuclear, biological or chemical weapons, or missiles capable of delivering such weapons. Silicon Labs disclaims all express and implied warranties and shall not be responsible or liable for any injuries or damages related to use of a Silicon Labs product in such unauthorized applications.
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FAQ
- Q: Can the CP2102C be used as a drop-in replacement for all CP210x devices?
- A: The CP2102C is virtually a drop-in replacement for devices like CP2102, CP2102N, and CP2104 with minimal hardware changes. For other devices, slight package or feature differences may require minor hardware modifications.
- Q: What is the recommended baud rate for the CP2102C?
- A: The CP2102C supports a maximum baud rate of 3Mbps.
Documents / Resources
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SILICON LABS CP2101 Interface Controller [pdf] User Guide CP2101, CP2101 Interface Controller, Interface Controller, Controller |