Welding machine control embedded system design

1 system hardware architecture
Embedded systems based welding machine control system design, to AT91RM9200 as the system core microprocessor control system requirements based on expansion of SDRAM, SRAM, Flash, keyboard, LCD display circuit parameters can be adjusted in real time, display and error alarm, RS485 serial interface for data transfer communications, infrared remote control can be. System hardware structure shown in Figure 1.
2.1 System Power Works
AT91RM9200 is a complete system built around the ARM920T processor chip. It has a wealth of system and conveyor belt and standard interfaces, making low-power, low-cost embedded industrial products. AT91RM9200 offers a full-function power management controller (PMC), to optimize the overall system power consumption, and to support normal, idle, slow clock and Standby mode, to provide different power levels and incident response delay time [1]. In idle mode, ARM processor clock and wait for the next interrupt is disabled (or master reset); slow clock mode is selected after reset mode, in this mode the main oscillator
Oscillator circuit is the basis for sending and receiving equipment, its role is to produce a certain frequency of the AC signal, an energy conversion device - the DC can be converted to a certain frequency electric oven. Off to reduce power consumption and PLL; Standby mode is the slow clock mode and idle mode of combination, which enables the processor to quickly respond to wake events, and maintains a low power consumption. When the system outside normal working hours from the DC power supply and battery charging, disconnect the external power supply automatically switches to the internal backup battery.
2.2 Power Circuit Design
AT91RM9200 has five types of power supply pins: VDDCORE pin for power supply to the core, typically 1.8 V; VDDPLL, VDDOSC respectively, to the PLL or oscillator power supply, typically 1.8 V; VDDIOP, VDDIOM were used to the outside set I / O port cable, USB transceiver and the external bus interface I / O port line power supply, usually 3.3 V. In addition, the system's keyboard, display circuit supply voltage of +5 V power supply needs. Therefore, the control system needs to use three groups of power. Through control of the whole ball mill system requirements and performance analysis to determine the system load current is about 3 A. Therefore, the system power supply voltage regulator chips use a series of ON's LM2576 voltage regulator, the external DC power supply voltage regulator into the system needs to +3.3 V and +5 V power supply. As the power supply requirements of the system kernel 1.8 V, so the system should be used two power conversion circuit. This selection of TI's micro-power, low dropout voltage PMOS regulator (LDO chip) TPS72518 chip as the core power conversion, the +3.3 V regulator to +1.8 V, supplies power for the processor core. System power supply circuit shown in Figure 2. Figure 2 shows the power supply decoupling and other embedded systems, PCB design. C3, C6 is the voltage regulator flexo printing machine bypass capacitor in the circuit which enables the circuit to stabilize access to work; C2, C5, C8 and stability for the output capacitor, for reducing the output ripple, noise and output load current change impact good results, according to the regulator's own work requirements, were selected capacitance 10 μF, 100 μF electrolytic capacitor