Interpretation of ARM7 core microcontroller LPC2148 Ethernet interface circuit

微盟ME2188A33PG

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

Kaixin micro test ESD18VB03-0201

SMD aluminum electrolytic capacitor

The embedded master module uses the LPC2148 microcontroller based on the ARM7TDMI-S core, which is highly integrated. Embedded 40kB on-chip static RAM and 512kB on-chip flash memory, on-chip integrated ADC, DAC converter, watchdog, real-time clock RTC, 2 UARTs, 2 I2C and SPI and other bus interfaces, and USB2.0 full speed interface. It is convenient to expand the USB interface, JTAG debugging interface, touch screen, less external expansion chip, and adopt ultra-small LQFP64 package, which ensures the miniaturization of the instrument. And the circuit is relatively simple, reducing the cost of development and production. The chip can achieve a working frequency of up to 60MHz, and has strong functions, which can meet the requirements of the embedded system μC/OS-II and humanized human-machine interface. All interfaces of the LPC2148 are used in this design.

The Ethernet interface section uses the ENC28J60 with integrated SPI interface and 10 BASE-T PHY. The overhead of the main controller I/O port is greatly reduced. The ENC28J60 is compliant with all IEEE 802.3 specifications and employs a range of packet filtering mechanisms to limit incoming packets. It also provides an internal DMA module for fast data throughput and hardware-supported IP checksum calculations. Communication with the host controller is accomplished through two interrupt pins and SPI with data rates up to 10 Mb/s. Two dedicated pins are used to connect the LEDs for network activity status indication.

Figure 2 Ethernet interface circuit diagram

The LED module uses 20 LEDs of 6 wavelengths. The multi-wavelength design makes the measurement more targeted and the measurement data is more efficient. Our design is able to measure the brightness of each LED through the CCD, and then the LPC2148 uses the point correction function to control the size of the LED current, so that the brightness between the LEDs is consistent, further improving the accuracy of the measurement. The network chip used in this design is a stand-alone Ethernet controller with an SPI interface, which occupies less I/O ports of the MCU. The CCD module mainly includes the whole machine power supply, CPLD, linear array CCD sensor, operational amplifier and high precision AD converter.