Programmer the programmer will plug into any serial

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Unformatted text preview: disIn-System crete components. Programmer The programmer will plug into any serial port of any PC. The AT90S1200 doesn’t come with a hardware UART, but the software will run a half duplex UART by using the Timer/Counter0 to clock data. The AT90S1200 also takes care of programming the target AVR by running the Master SPI entirely in software. The schematics to the programmer can be seen in Figure 4. Power to the AT90S1200 is taken from the target system. The negative voltage needed to communicate serially with the PC is stored in C100 when receiving a logical one (negative line voltage). The transmit line is fed with this negative voltage from C100, when transistor Q100 is closed. This sends a logical one on the transmit line. Logical zeros (positive voltage) is sent by opening Q100, connecting VCC (actually VCC - 0.2V) to the transmit line. Some older PC systems might have serial port not accepting voltages below +10 volts as logical zero. This, however, is not a problem with the majority of existing PCs. The file avr910.asm contains the firmware for the AT90S1200. Figure 4. A Low-cost In-System Programmer PAD J100 1 R104 4K7 BC857C Q100 RXD TXD 6 2 TRANSMIT 3 RECEIVE 7 8 5 R100 4K7 4 9 D100 9-PIN D-SUB FEMALE R105 4K7 BAS16 C101 R103 4K7 R101 4K7 R102 4K7 J101 VCC 100N MOSI AT90S1200 20 1 2 3 6 7 8 9 11 5 VCC GND RESET AIN0/PB0 PD0 AIN1/PB1 PD1 PB2 PD2/INT0 PB3 PD3 PB4 PD4 PB5 U100 PD5 PB6 PD6 PB7 XTAL1 XTAL2 10 12 13 14 15 16 17 18 19 4 GND 2 1 4 3 6 5 MISO SCK RESET CONNECTOR AS SEEN FROM BELOW R106 1M0 BC847C Q101 1.0uF 20V + C100 D101 BAS16 4 MHZ XC100 GND 10 AVR910 0943E–AVR–08/08 AVR910 Part List Table 14. Part List QTY Position Value Device Tolerance Vendor Comment 1 C100 1U0/20V CE1U020V 20% PHILIPS +++ TANTAL CAPACITOR, SMD, (EIA3216) 1 C101 100N/50V C08B100N 10%_X7R MURATA +++ CERAMIC CAPACITOR, 0805, X7R 2 D100,D101 75V/100MA BAS16 PHILIPS +++ SWITCH DIODE, SO-23 PACKAGE 1 J100 9 PIN DSUB-9FSOL HARTING +++ 9 PIN D-SUB, FEMALE, SOLDER, 1.6 MM ROW SPACING, 2.54 MM PIN 1 JCABLE 6 PIN HEADER6FC HARTING +++ 6 PIN HEADER (IDC), FEMALE, CABLE MOUNT 1 Q100 45V/100MA BC857C PHILIPS +++ SMD NPN TRANSISTOR, SO-23 PACKAGE 1 Q101 45V/100MA BC847C PHILIPS +++ SMD PNP TRANSISTOR, SO-23 PACKAGE 6 R100-105 4K7 R08_4K7 1% KOA +++ RESISTOR, 0.125W, 1%, 0805 1 R106 1M0 NOT_USED 1% KOA +++ RESISTOR, 0.125W, 1%, 0805 1 U100 SOIC-20 AT90S1200-4SC ATMEL AVR MICROCONTROLLER, 20 PIN SOIC 1 XC100 4.0MHZ CSTCC4.00MG 0.5% MURATA/AVX +++ CERAMIC RESONATOR, 4.00 MHZ, SMD (AVX: PRBC-4.0 B R) 1 HOUSING 9 PIN D-SUB HOUSE 0.5% AMP +++ 9 PIN D-SUB PLASTIC HOUSING 1 CABLE 6 LEAD FLATCABLE HARTING +++ FLATCABLE, 6 LEAD, 300 MM 1 PCB FR4/1.6MM A9702.3.1000.A ATMEL PRINTED CIRCUIT BOARD NO. A9702.3.1000.A 11 0943E–AVR–08/08 Headquarters International Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 Atmel Asia Room 1219 Chinachem Golden Plaza 77 Mody Road Tsimshatsui East Kowloon Hong Kong Tel: (852) 2721-9778 Fax: (852) 2722-1369 Atmel Europe Le Krebs 8, Rue Jean-Pierre Timbaud BP 309 78054 Saint-Quentin-enYvelines Cedex France Tel: (33) 1-30-60-70-00 Fax: (33) 1-30-60-71-11 Atmel Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: (81) 3-3523-3551 Fax: (81) 3-3523-7581 Technica...
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