Shulou(Shulou.com)06/03 Report--

Shanghai Juwei is a domestic company focusing on chips and related system design, providing the most cost-effective general wireless chips and wireless sensor chips and solutions, and has become a major supplier of wireless sensor nodes. Its core technical capabilities cover RF, simulation, SOC and system software design.

Shanghai Giant Micro MG123 is a low-power, low-cost BLE transceiver with integrated transmitter, receiver, GFSK modem and BLE baseband processing. This series of products are packaged with MSOP10, and only need to match low-cost MCU and a few peripheral passive devices to realize BLE remote control, Bluetooth electronic scale and other applications. Nordic Bluetooth chip can be replaced.

The power supply voltage is 1.9 to 3.6 and can be powered by a button battery (3.0v).

3uA standby current

20mA@0dBm continuous launch

MSOP10 encapsulation with few peripheral BOM

Only low-cost MCU is needed.

Data and control interface

MG123 communicates with MCU through a 3-wire SPI interface and IRQ signals, and the interface includes the following signals:

IRQ (this signal is active low and is controlled by maskable interrupt sources)

CSN (SPI signal)

SCK (SPI signal)

MOSI (SPI signal)

The MOSI signal is used for input and output. MCU can use 3 GPIO to simulate SPI, we provide 3-wire SPI reference C source code.

Fig. 1 SPI sequence diagram

Applied circuit schematic diagram

The following figure is a typical application circuit schematic diagram of MG123.

Figure 2 schematic diagram of an example application

Considerations for PCB cabling

Power source

The wiring of power cord and ground wire is directly related to the performance of the product, and the noise interference is reduced to a minimum. When wiring, it is necessary to widen the width of ground wire and power cord as far as possible, ground wire > power cord > signal wire, usually signal line width 0.2~0.3mm, power line width 1.2~2.5mm, use large area copper layer as ground wire, and spread all useless spaces into the ground on PCB.

Two capacitors are added to the power supply. If LDO is used for power supply, 1uF and 0.1uF are used for filtering; if button battery is used for power supply, capacitance values 10uF and 10uF are used to stabilize the voltage.

Crystal oscillator

The crystal oscillator circuit should be as short and symmetrical as possible, close to the chip to reduce the influence of noise interference and distributed capacitance. The crystal oscillator shell should be well grounded.

Antenna

Antenna has a great impact on communication, please use a mature 2.4GHz antenna structure, or strictly according to the requirements of the antenna board. In general, the PCB antenna needs clearance, and the distance between the antenna and the ground (copper laying) should be greater than 0.5mm. Do not have components or metal structures around the antenna.

The line between the chip ANT and the antenna should not be too long, and the linewidth should take into account the requirement of impedance matching.

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