nRF905 is a monolithic RF transmitter chip launched by Nordic Company in Norway . It adopts 32-pin 5mm & TI mes; 5mm QFN package and works at 3 ISM (industrial, scientific and medical) channels of 433, 868 and 915MHz, of which 433 in domestic Bands are free to use. nRF905 is composed of frequency synthesizer, receiver demodulator, power amplifier, crystal oscillator, modulator and other functions. It can also have good communication effect without external SAW filter. The nRF905 can communicate with any MCU using the SPI interface, in which the address, output power and communication channel can be configured through the program, so it can be used for multi-computer communication. nRF905 incorporates ShockBurstTM technology, which can automatically process the header of the data packet, and has a built-in CRC check function to ensure reliable data transmission. The power consumption of nRF905 is very low. When transmitting at a power of -10dBm, the working current is only 11mA; while the working current of the corresponding receiver is only 12.5 mA. The chip can set the idle mode and shutdown mode by software, which is easy to energy-saving design. It is suitable for many applications such as industrial data acquisition, wireless alarm and security systems.
Basic features of nRF905
(1) 433Mhz open ISM frequency band for license-free use;
(2) The maximum working rate is 50kbps, and the communication distance can reach about 300 meters;
(3) High-efficiency GFSK modulation, strong anti-interference ability, especially suitable for industrial control occasions;
(4) The working frequency can be set by software to meet the needs of multi-point communication and frequency hopping communication;
(5) Built-in hardware 8, 16-bit CRC error detection and point-to-multipoint communication address control;
(6) Low power consumption 1.9 - 3.6V work, only 2.5uA in standby mode;
(7) The switching time of the transceiver mode is only 650us;
(8) SPI programming interface, the address can be set by software, and the address can be up to 2 to the 32th power;
(9) Integrated address matching, carrier sense, and sending and receiving completion status indication functions;
(10) TX Mode: In the case of +10dBm, the current is 30mA; RX Mode: 12.2mA;
(11) Standard 2.54mm DIP pitch interface, convenient for embedded applications;
At the same time, in order to facilitate user development, we provide supporting evaluation kits to escort product development, greatly accelerate wireless application development, and avoid unnecessary misunderstandings.
nRF905 adopts Nordic's VLSI ShockBurst technology. ShockBurst technology enables nRF905 to provide high-speed data transfer without requiring expensive high-speed MCU for data processing/clock overlay. By putting the high-speed signal processing related to the RF protocol into the chip, nRF905 provides an SPI interface to the microcontroller of the application, and the speed is determined by the interface speed set by the microcontroller itself. The nRF905 reduces the average current consumption in the application by reducing the speed of the digital application part through the ShockBurst mode of operation when the RF is connected at maximum rate. In ShockBurst RX mode, the address matching AM and data ready DR signals inform the MCU that a valid address and data packets have been received respectively. In ShockBurst TX mode, nRF905 automatically generates preamble and CRC check code, data is ready DR signal informs MCU that data transmission has been completed. All in all, this means reducing the memory requirements of the MCU, which means reducing the cost of the MCU, and at the same time reducing the software development time.
1) Typical ShockBurst TX mode:
nRF905 adopts Nordic's VLSI ShockBurst technology. ShockBurst technology enables nRF905 to provide high-speed data transfer without requiring expensive high-speed MCU for data processing/clock overlay. By putting the high-speed signal processing related to the RF protocol into the chip, nRF905 provides an SPI interface to the microcontroller of the application, and the speed is determined by the interface speed set by the microcontroller itself. The nRF905 reduces the average current consumption in the application by reducing the speed of the digital application part through the ShockBurst mode of operation when the RF is connected at maximum rate. In ShockBurst RX mode, the address matching AM and data ready DR signals inform the MCU that a valid address and data packets have been received respectively. In ShockBurst TX mode, nRF905 automatically generates preamble and CRC check code, data is ready DR signal informs MCU that data transmission has been completed. All in all, this means reducing the memory requirements of the MCU, which means reducing the cost of the MCU, and at the same time reducing the software development time.
1) Typical ShockBurst TX mode:
①. When the application MCU has a remote control data node, the address TX-address of the receiving node and the valid data TX-payload are transmitted to the nRF905 application protocol or MCU to set the interface speed through the SPI interface;
②, MCU sets TRX_CE and TX_EN high to activate nRF905 ShockBurst transmission;
nRF905 ShockBurst：
The wireless system is automatically powered on
The data packet is completed (add preamble and CRC check code)
Data packet transmission (100kbps, GFSK, Manchester encoding)
④. If AUTO_RETRAN is set to high nRF905 will send data packets continuously until TRX_CE is set to low;
⑤. When TRX_CE is set to low, nRF905 ends data transmission and automatically enters standby mode.
2) Typical ShockBurst RX mode
①. Select ShockBurst mode by setting TRX_CE high and TX_EN low;
②, after 650us, nRF905 monitors the information in the air;
3. When nRF905 finds a carrier with the same frequency as the receiving frequency, the carrier detection CD is set high;
④. When nRF905 receives a valid address, the address matching AM is set high;
⑤. When nRF905 receives a valid data packet (CRC check is correct), nRF905 removes the preamble, address and CRC bits, and data ready (DR) is set high;
⑥. MCU sets TRX_CE low and enters standby mode and low current mode;
⑦. MCU can read valid data through SPI interface at a suitable rate;
8. When all valid data is read out, nRF905 sets AM and DR low;
⑨, nRF905 will be ready to enter ShockBurst RX, ShockBurst TX or Powerdown mode.
3) Power down mode
In power-down mode, the nRF905 is disabled and current consumption is minimal, typically below 2.5uA. When entering this mode, the nRF905 is inactive. At this time, the average current consumption is the smallest and the battery life is the longest. In Power-down mode, the contents of the Configuration Words remain unchanged.
4) STANDBY mode
Standby mode ensures the shortest startup time of ShockBurstRX and ShockBurstTX while keeping current consumption to a minimum. When entering this mode, a portion of the crystal oscillator is active. The current consumption depends on the crystal oscillator frequency, such as: when the frequency is 4MHZ, IDD=12uA; when the frequency is 20MHZ, IDD=46uA. If uPCLK (Pin3) is enabled, the current consumption will increase. and depends on load capacitance and frequency. In this mode, the contents of the Configuration Words remain unchanged.
Shenzhen Kinetic Century Technology Co., Ltd.
Zhao Zhihong 2355892364
Shenzhen Kinetic Century Technology Co., Ltd.
Zhao Zhihong 2355892364