A universal programmer is a programmer that can be commonly used by different devices (such as produced by different companies and different architectures). It is a subclass of the programmer’s functional classification, as opposed to a dedicated programmer.
This multifunctional universal device is powerful and supports programming of more than 400 commonly used chips, including MCS-51 series, PIC series, AVR series single-chip microcomputers, and EPROM, EEPROM, FLASH, I2c, 93Cxx and other series. The circuit principle is as shown in the figure, which is divided into six units: programming voltage adjustment, writing data, address data control, addressing, reading data and serial programming.
1. Programming voltage adjustment unit
The programmer uses 24V regulated DC power supply. Use a diode connected in series to the 7812 ground pin to pull up the ground level to increase the output voltage. Different combinations of 2-position DIP switches can be used to connect or short-circuit the diode. For example: When the 2-position DIP switch is in the ON position, the 7812 ground terminal is connected in series with lN4148, and the output voltage is 12.7V; when it is 2 positions. When the DIP switches are all in the OFF position, the 7812 ground terminal is connected in series with lN4148 and 8.2V regulator tube, and the output voltage becomes 2lV.
The programming voltage Vpp and VCC are only in the on state when programming and reading the chip, and the programming voltage is controlled by the PIN1 and PIN16 of the parallel port of the computer. When PIN1/16 is at a low level, Q4 and Q2 are in an off state; when PIN1/16 is at a high level, Q4 and Q2 are turned on, and the programmed Vpp/Vcc is obtained at the collector of Q2.
In hardware, the pin driver of the universal programmer adopts an overall structure with various functions. And only new software is needed to support new devices (such as PRESTO from ASIX, GALEP from CONITEC in Germany.and chipProg-40 from PHYTON in the US) It has high flexibility to meet current and future device needs. Generally, each pin of the universal programmer lock base can use as a clock signal, data bus, address bus, a control bus, ground, power line, VCCQ voltage, VPP programming voltage, dedicated bus for pin contact measurement, etc. The driving voltage can adjust from 1.8V to 25.0V.
Another essential feature of the universal programmer is that it has a detection function. Usually, the locking seat is floating, and any IC placed in it will not cause a short circuit or burn out the IC due to the first voltage. When programming and other operations, the universal programmer first uses a unique dedicated bus to detect the contact condition of the pins with a weak signal and operates only when the contact is good.
Compared with ordinary non-universal programmers, the universal programmer has the advantages of convenient function upgrade, universal adapter, and fast speed. At the same time, the universal programmer’s unique detection function effectively prevents losses caused by reversed components, short circuit of some pins, and poor contact.
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