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Interrupts
Published in Syed R. Rizvi, Microcontroller Programming, 2016
Here we briefly outline some of the other nonmaskable interrupts. Earlier in this chapter we discussed SWI instruction. The illegal opcode fetch is an interrupt requested when an illegal opcode is detected. The computer operating properly (COP) failure is a nonmaskable interrupt designed to detect software processing errors. The clock monitor failure is responsible for detecting problems in the proper running of the system clock. The Power-On Reset (POR) is designed to initialize the internal microcontroller circuits. The nonmaskable interrupt priority cannot be changed. The priority rankings are shown in Table 9.2. Overall, the nonmaskable priority is higher than the maskable interrupts. We will discuss in detail the nonmaskable interrupts and when we will use them in our programming projects.
Synchronous Sequential Circuits
Published in Sajjan G. Shiva, Introduction to Logic Design, 2018
It is important to note that for the circuit to operate properly, a sequential circuit must be initialized to its starting state before the input sequence is applied. It is common practice to include a master-clearcircuit that can be used to initialize each flip-flop in the circuit once the power is turned on. Some circuits include a power-on reset circuit that performs the initialization as soon as the power is turned on. Chapter 8 provides the details of one such circuit.
Distributed Motor Controller for Operation in Extreme Environments
Published in John D. Cressler, H. Alan Mantooth, Extreme Environment Electronics, 2017
The POR circuit detects the power applied across the electronics module and generates a “power good” active low signal for the FPGA once all of the power supplies are within range. Before this power good signal, the FPGA will remain idle. The POR accepts five resistor-divided voltages from power supplies and compares their values to an internally generated 1.2 V reference. Tolerances for the power supplies are selectable by the FPGA to 5% or 10% under/over nominal voltage supply levels.
Fractional-N phase-locked loop for split and direct automatic frequency control in A-GPS
Published in International Journal of Electronics, 2018
Chester Sungchung Park, Sungkyung Park
Building blocks of the fractional-N PLL include a low-leakage PFD, a charge pump and a loop filter with precharge circuitry, a ring-oscillator-type multiphase VCO, a frequency divider implemented as digital counter, an additional divide-by-12 frequency divider, a digital DSM and some digital logic. The precharge circuitry is used for precharging an internal node of the loop filter to attain faster settling. The digital blocks in the MS part of Figure 2 are all implemented by means of standard-cell-based semi-custom design while all the blocks in the all-digital part of Figure 2 are implemented by means of RTL design and synthesis. In addition, an LDO regulator is used to achieve a high power supply rejection ratio and low PLL output noise while power-on-reset circuitry (connected to the LDO) is used to initialise the digital counter to a valid state (or a non-forbidden state).