As the Internet of Things (IoT) deeply penetrates thousands of industries, sub-GHz radio frequency chips, as the core communication units of low-power wide area networks (LPWANs), are facing the key challenge of "balancing transmission performance and energy efficiency" - there is often a "constraint relationship" between transmission distance, data rate and operating power consumption. Increasing transmission distance and data rate will increase chip power consumption, thereby shortening terminal battery life and limiting deployment scenarios.
However, with the explosive demand for "ultra-long battery life, reliable transmission and multi-protocol signal compatibility" in fields such as industrial Internet of Things, home security, building automation and wireless sensor networks, breaking through this traditional "constraint relationship" and achieving coordinated optimization of high performance and low power consumption has become one of the core issues in the technological evolution of the Internet of Things industry.
Recently, to further meet the communication needs of IoT terminals for high transmission performance and low operating power consumption and break through the performance bottleneck of Sub-GHz RF chips, HOPERF has specially designed a special feature for the Sub-GHz RF transceiver chip CMT2312A - fast switching of pre-stored configurations.
As shown in the figure below, the fast switching of pre-stored configurations means that the CMT2312A's internal RF controller quickly transfers the configurations pre-stored in the chip's internal OTP ROM to the chip registers via DMA (Direct Memory Access). This bypasses the tedious process of configuring register addresses one by one through the external MCU's SPI, speeding up chip configuration and enabling faster entry/switching of working states. This effectively saves time and resources, making it particularly suitable for applications that require frequent switching between different configurations and have strict requirements on switching time.
CMT2312A-Quick Switching Pre-stored Configuration Diagram
Note: OTP ROM (One-Time Programmable Read-Only Memory) is a memory used to store permanent configuration data required for chip operation (such as RF parameters, calibration information, or encryption keys). Its core feature is that it can only be written once; once the data is fixed, it cannot be modified, making it suitable for scenarios requiring high reliability and security. The CMT2312A supports up to seven pre-stored configurations, and can switch to any of these seven configurations using the API_CMD command.
For example, when a user's receiver needs to adaptively receive three sets of protocol signals with different settings from a transmitter (such as Protocol A, Protocol B, and Protocol C, all of which contain pilot signals of sufficient length when sending signals), the CMT2312A, which has the function of quickly switching pre-stored configurations, can act as a receiver in this communication scenario. The corresponding pre-stored configurations can be burned into the software to quickly switch back and forth between different pre-stored configurations for monitoring.
3 sets of protocol signals with different settings from the transmitter
Because the pilot signal is long enough, the CMT2312A, acting as a receiver, can lock the corresponding pre-stored settings during the monitoring process by detecting pilot signals that meet the above three sets of protocols as the locking condition, thereby achieving adaptive reception of signals with different protocols.
In addition, based on the mechanism of switching monitoring back and forth between different pre-stored configurations, the CMT2312A acting as a receiver also supports the ultra-low power combined operation mode of "DutyCycle+SLP" - that is, by introducing sleep time, low-power monitoring is achieved in the form of duty cycle.
CMT2312A operating timing diagram based on the above conditions
It is worth mentioning that after testing the above solution, HOPERF Laboratory concluded that using fast switching of pre-stored configurations can not only reduce chip power consumption but also save the time of software configuration parameters compared with switching configurations through an external MCU. In addition, thanks to the CMT2312A's internal DMA-level switching of pre-stored configurations, the time for switching internal configurations is only about 150us.
The CMT2312A is an ultra-low-power , high-performance , highly integrated RF transceiver suitable for various 113 to 960 MHz wireless applications, including OOK, 2(G)FSK, 4(G)FSK, and (G)MSK . It supports multiple data packet formats and codecs , flexibly meeting diverse application requirements. Its high +20dB transmit power and -122dBm sensitivity significantly optimize application link performance.
In terms of functionality, the CMT2312A also supports 128-byte Tx/Rx FIFO , rich GPIO and interrupt configurations , Duty-Cycle operation mode , channel sensing , high-precision RSSI , low-voltage detection , power-on reset , low-frequency clock output , fast frequency hopping , and squelch output , greatly broadening the product's application adaptability .
CMT2312A system functional block diagram
As shown in the functional block diagram above, the CMT2312A uses a low-IF architecture consisting of an LNA, MXR, PGA, ADC, and PLL to achieve wireless reception below 1 GHz. It also uses a PLL and PA architecture to achieve wireless transmission below 1 GHz. The CMT2312A achieves excellent transmit and receive RF performance without requiring additional RF switching components.
CMT2312A Typical Parameters Chart (Excellent RF Performance)
It is worth mentioning that the CMT2312A also supports a variety of special features such as fast switching of pre-stored configurations, fast and stable automatic frequency correction (AFC), three clock recovery systems (CDR) with different characteristics, fast and accurate effective signal detection (PJD, RSSI), ultra-low power consumption (SLP) and duty cycle reception, fast transmit or receive frequency hopping, carrier sense multiple access (CSMA), automatic ACK and retransmission, antenna diversity, etc.
In terms of automatic frequency control (AFC), the CMT2312A has industry-leading performance. Compared with other similar products, it can eliminate the frequency difference between TX and RX in a shorter time (8-10 symbols) to achieve higher sensitivity. Moreover, within the same bandwidth, the CMT2312A can also identify larger frequency differences.
In terms of data rate clock recovery (CDR), the CMT2312A supports three clock recovery systems: COUNTING, TRACING, and MANCHESTER. It can recover a clock signal synchronized with the data rate while receiving data. The TRACING system can withstand data rate deviations of up to 15.6%, which is unattainable by other similar products in the industry.
Note: For more details on the quick switching of pre-stored configurations, please refer to the AN244 document and related product specifications on the HOPERF official website.
