introduction
The nRF24E1 is a high-speed 1Mbps single-chip wireless transceiver chip embedded in a high-performance microcontroller core from Nordic.
Compared with Bluetooth, nRF24E1 has no complicated communication protocol, is completely transparent to users, and can communicate freely between the same products. More importantly, the nRF24E1 is cheaper than Bluetooth and has a cost advantage. Therefore, the nRF24E1 is a low-cost RF system-level chip with small size, low power consumption and few external components.
nRF24E1
The block diagram of the wireless transceiver integrated chip nRF24E1 is shown in Figure 1.
nRF24E1 embedded in the 2.4GHz wireless core nRF2401, with a global open 2.4GHz frequency band, 125 channels, to meet the needs of multi-frequency and frequency hopping. Integrated enhanced 8051 microprocessor core, 9 10-bit ADC, sampling rate 100kHz, built-in voltage reference, power detection, configurable PWM output, UART asynchronous serial port, SPI synchronous communication serial port; built-in CRC test and multi-point communication control, suitable Point-to-multipoint communication.
Using 1.9~3.6V power supply, very few peripheral circuits, all working parameters such as transmit power and working frequency are all set by software. All high-frequency components, including inductors and oscillators, are all integrated inside the chip, with good consistency and performance. Stable and unaffected by outside influences. Moreover, each chip can be set up to 40-bit address through software, and data will be output only when the local address is received (providing an interrupt indication), which is convenient for programming. Built-in CRC error correction hardware circuit and protocol, it is very convenient for software developers to program, because it is not necessary to complete the error correction operation by the single-chip microcomputer, it can reduce the difficulty of wireless application development.
The DuoCeiver technology can receive data from two nRF2401 simultaneously. The basic principle is that DuoCeiver is a simultaneous dual channel receive mode. The nRF24E1 can receive data from two 1 Mbps transmitters (eg nRF24E1, nRF2401 or nRF2402) separated by 8 MHz through an antenna interface. The outputs of the two data channels are fed back to two separate interface pins:
Data channel 1: CLK1, DATA, DR1
Data channel 2: CLK2, DOUT2, DR
Figure 1 nRF24E1 block diagram
Figure 2 DuoCeivertm simultaneous dual receive channel
DuoCeiver technology provides two separate dedicated digital channels for RX, replacing the requirements for two separate receiving systems. The DuoCeiver shown in Figure 2 simultaneously receives the channel. The frequency of digital channel 2 is 8 MHz higher than that of digital channel 1 to ensure normal reception.
The nRF24E1 also features a high rate of 1Mbps, which is higher than Bluetooth and has high data throughput. Built-in WTD watchdog with data slot and data clock recovery.
Application circuit
Figure 3 nRF24E1 connected to a single-ended 50W antenna RF circuit
The RF circuit of the nRF24E1 connected to the single-ended 50W antenna is shown in Figure 3.
This circuit diagram contains all the circuitry needed to implement the nRF24E1 in a short-range communication system. All digital I/O signals used around the wiring diagram, the A/D inputs can be connected to the peripheral parts used by the user. The serial EEPROM program code required for the nRF24E1 is included in the circuit. The EEPROM is a standard 2XX320 SPI type. The circuit has its own power supply and grounding. The power supply of this part of the application circuit should be separated from any high current peripheral power supply filtering. A single-ended 50W antenna uses a different single-ended matching network.
The following points should be noted in practical applications:
The available frequency band is determined by local adjustment;
The crystal frequency should be selected from the different values ​​specified in the five configuration tables 4, 8, 12, 16 and 20 MHz, usually 16 MHz when the data rate is 1 Mbps;
The data rate can only be 250kbps or 1000kbps;
The non-embedded antenna has a load impedance of 400W. â–
references
1. Nordic VLSI. 2.4Ghz RF transceiver with embedded 8051 compaTIble microcontroller and 9 input, 10 bit ADC. 2003.7
2. Nordic VLSI. nRF24E1 and nRF24E2 RF layouts. 2003.5
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