PUGAUGE Hardware

Overview

PUGAUGE Hardware consists of:

• 8-Character Segmented LCD 14-segment Display
• Atmel AVR ATmega6490A AVR microcontroller
• Atmel ISP Connection
• Arduino Upload Serial Interface
• A Status LED on MCU port PB0

Build notes

Connection of ATmega6490

In the first development version all circuitry is mounted on a solderless breadboard:

• The ATmega6490 is mounted on the BBR.
• LCD-Voltage Buffer Capacitor: 3x220nF FKC in parallel from ATmega6490 Pin 1 / BBR Pin 76 to GND
• System Status LED: Port line PB0 (ATmega6490 Pin 19 / BBR Pin 94) to 330 Ohm to yellow LED to GND
• In-System-Programmer (IST) USPasp connected to 10-pin 2x5 100mil-spaced Connector:

See also http://nerdyelectronics.com/usbasp-tutorial/ :

                                                           Connector seen on board pins
USBasp pin number USBasp pin MCU Pin                          +---+---+---+---+---+
1 	          MOSI       MOSI                             | 2 | 4 | 6 | 8 |10 |
5                 Reset      Reset                            +---+---+---+---+---+
7                 SCK        SCK                              | 1 | 3 | 5 | 7 | 9 |
9                 MISO       MISO                             +---+--++---++--+---+
10                GND        GND                                     +-----+
2                 Vcc        Vcc                           NOTE1: the USBasp ribbon cable has a RED marking on the wire going to in 1
                                                                  thus, it should be on the LEFT side of above connector!
                                                           NOTE2: the USBasp ribbon cable connector has a protrusion in the near pin 5. Look for this to be sure!

Signal name	description	10-pin-conn pin number	ATmega6490 pin name	ATmega6490 pin number	BBR pin number
MOSI	data from programmer to MCU	1	MOSI	21	96
Reset	reset pulse to MCU	5	Reset	30	5
SCK	serial clock to MCU	7	SCK	20	95
MISO	data from MCU to programmer	9	MISO	22	97
GND	Ground reference	10	GND	99,11,32,81	74,86,7,56
VCC	+5V supply from programmer	2	VCC	100,10,31,80	75,85,6,55

Serial-USB Adapter, connected to TXD/RXD of UART0 of ATmega6490 PLUS Auto-Reset-Circuit using DTR of Serial-USB

Signal name	description	FT323-adapter pin	ATmega6490 pin name	ATmega6490 pin number	BBR pin number
GND	Ground reference	GND	GND
TXD	data from USB to MCU	TXD	RXD/PCINT0/PE0	2	77
RXD	data from MCU to USB	RXD	TXD/PCINT1/PE1	3	78
DTR	DataTerminalReady from USB	DTR	100nF Capacitor to "Reset"-Pin PLUS: pullup-10k-Resistor to +5V parallel to 1N4148Diode Cathode to +5V, Anode to Reset PLUS "RESET"Button to GND	30	5

Optional Debug-Assist Serial-USB-Adapter, connected to a GPIO Port driven by Software-UART

This is an output-only software/bit-banging asynchronous serial output used for outputting debug information.

The serial output of this interface is connected to GPIO Port PB6 and may be hooked up to an additional Serial-USB adapter.

This debug output port is served by the PUGAUGE debug library, which also provides a few convenience debug output functions and shortcut macros which can be enabled or disabled at compile time additional to route debug output to either the PUGAUGE LCD and/or the debug serial port.

TQFP-100 Breakout board

When soldering the AVR6490 Chip in the TQFP-100 case to it's breakout board, I made an error:

I turned it 90 degrees to the right. Therefore Pin 1 of the chip appears at Pin 76 of the breakout board.

The algorithm to find the BBR pin when knowing the pin number on the TQFP-100 package of the ATmega6490 is:

BBR-pin = (TQFP-pin + 75) MOD 100

There will be a translation table on the PUGAUGE Tables page.

Connection from the D301 LCD to the PUGAUGE MCU is documented on the PUGAUGE Tables page.