Control AVR Downloader

This peripheral is a module single chip with microcontroller ATmega8535 and ability of serial communications in UART and In-System Programming (ISP). This module is completed with array pad that is service the purpose of place for addition network. This compatible module for user is wishing having experiment, makes prototyping, or makes the application of simple. Example of the application of its is as display controller LED, controller driver motor, motion controller of robot, to changes data with computer, digital sensor reader and also analogue sensor, and memory access and PPI.

Program which has been written down into ATmega8535 serve the purpose of initial testing program. This program will test PD0 and PD1 as serial communications line then releases waving box at all of pin Port A, Port B, Port C and Port D.

Testing stages:

· Arranges jumper J2 and J3 that PD0 and functioning PD1 as serial communications line of UART RS-232 ( jumper connected).

· Connects serial cable to COM computer port and RJ11 at downloader.

· Connects source of tension 9 VDC to VIN.

· Implements program SERIAL1EXE. Determines COM port applied and depressed Test Serial.

· If serial communications run at ease, at program would seems to enlisting data sent received and is same (Sends = 0, Receives = 0; Sends = 1, Receives = 1; Sends = 2, Receives = 2, etc) and comes up windows to contain "Serial communications OK" !. If serial communications didn't go well, at program would seen difference of data received sent and comes up windows to contain "Serial communications of errors".

· Waving visible box passed oscilloscope or interfaced to network LED or DT-I/O LED LOGIC Tester so that seen its "ON-OFF" the LED.

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Control ISP AVR

AVR has two programming modes: Mode Programming Parallel (Mode Parallel) and Serial Downloading Mode (ISP mode).

At Mode Parallel, device which will be program placed at programming socket and required tension 12V at pin RESET. Communications between programmers and device is done with instruction of programming in parallel. Programming speed of twice the quickly is compared to ISP Mode. Way of this programming usually applied in pre-program and/or ISP Mode cannot be applied by factor design. Most of the programmer, except STK500 seen to be doesn't support this mode.

At ISP MODE, device communicates through SPI interface to programming and verification. This mode only requires three lines signal programming without tension of 12 Volts, causing earns target system program direct - ISP ( In-System Programming). But, ISP MODE cannot change fuse bit at some device, and some device doesn't have features ISP. Device like this must be program in parallel.

When using AVR with ISP Mode, target of board must be designed by considering function of ISP, what applies pin ISP: RESET, SCK, MISO and MOSI. Pin ISP can share between function of I/O and ISP satisfactorily. When using pin I/O having function of ISP, hopes paid attention of this things:

a. Inserts a resistor between pins RESET and reset network to avoid interference from reset network.

b. Ensures that action ISP doesn't generate effect at other function.

c. Men-drive doesn't from external network when operation ISP takes place, or if desired that way, need to be inserted a resistor.

d. Doesn't attribute to heavy burden because will influence function of ISP.

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