LB-6809-01

Features

• 68B09 CPU
• 8 MHZ crystal on card
  • CPU runs at 2 MHz
• Reset switch/power monitor
• Address decoder PLD drives RAM/ROM/IO chip selects
• 100x50mm card

Memory Map

• 0x0000-0x7FFF 32KB SRAM
• 0x8000-0x9FFF Free Space (8KB)
• 0xA000-0xBFFF Serial (ACIA)
• 0xC000-0xFFFF 16KB EPROM

Design

68B09 CPU

• 8 MHz clock
  • Runs effectively at 2 MHz

CPU

CPU Timing

Crystal

• Uses CPU internal oscillator

PLD

• ATF16V8B part
• TL866ii Plus Programmer

PLD Listing

• Latest PLD source code here
• Added code to blink LED

Name       LB-6809-01_PLD;
Partno     ATF16V8B;
Date       09/05/24;
Revision   01;
Designer   DOUG G;
Company    LAND BOARDS LLC;
Assembly   LB680901_U2;
Location   Rustbelt, US;
Device     G16V8;

/*
*/


/* Control inputs */
PIN    1   = CLK;
PIN    2   = CPUA12;
PIN    3   = CPUA13;
PIN    4   = CPUA14;
PIN    5   = CPUA15;
PIN    6   = CPUREAD;
PIN    7   = VPB;		/* Added as wire on Rev 1 PCB	*/
PIN    8   = VPA;
PIN    9   = VDA;
PIN    11  = D0;

/* Address Decode and Chip Select outputs */
PIN    12  = !ROMCS;
PIN    13  = !IOCS;
PIN    14  = !MEMRD;
PIN	15  = LED;
PIN    16  = !RAMCS;
PIN    17  = LEDSTR;
PIN    18  = RDY;

ROMCS = CPUA15 & CPUA14 & CPUREAD;

LEDSTR = CPUA15 & CPUA14 & !CPUREAD & VPB;

LED =  LEDSTR & D0
#      LED & !LEDSTR;

RAMCS = !CPUA15 &  CPUREAD				/* 0x0000-0x7FFF 32KB SRAM */
#       !CPUA15 & !CPUREAD & VPB
#       CPUA15 & !CPUA14 & !CPUA13 &  CPUREAD	/* 0x8000-0x9FFF Free (8KB	*/
#       CPUA15 & !CPUA14 & !CPUA13 & !CPUREAD & VPB;

IOCS = CPUA15 & !CPUA14 & CPUA13 & VPB;		/* 0xA000-0xBFFF Serial (ACIA)	*/

RDY = VPB;

MEMRD = CPUREAD;

Backplane connector

Software

• LB-6809 code examples
• asm6809 - portable cross assembler targeting the Motorola 6809
  • Features arbitrarily complex expressions (with most C-style operators available), forward references, macro expansion and conditional assembly
  • Output formats are: Motorola SREC, Intel HEX (and others)
  • asm6809 Manual
  • Using asm6809 version 2.13
  • asm6809-2.13-w64 Local copy
• MC6809-MC6809E 8-Bit Microprocessor Programming Manual (M6809PM/AD) © Motorola Inc., 1981
• MC6809 Rference Card

Build 6809 Assembly Code (Windows 64-bit)

• Run asm6809 in Windows CMD prompt window

[path_to_asm6809.exe_program\]asm6809 loop.asm -H -l -o loop.hex

• -H option creates hex record file to download to programmer
• -l fileName option creates listing file
• -o filename option followed by output file name

Programming using TL866

• Set From File Start(Hex) to 0x0C000 when loading hex record file into TL866i Plus programmer

ROM access test code (loop.asm)

• Assemble loop.asm
  • my path below, YMMV

..\..\M6809_Assembler\asm6809-2.13-w64\asm6809 loop.asm -H -l loop.lst -o loop.hex

• Source code (loop.asm)

		ORG $C000
RESVEC	BRA	RESVEC
		ORG	$FFFE
LBFFE	FDB	RESVEC	         ; RESET 

• .hex file

:02C0000020FE20
:02FFFE00C00041
:00000001FF

LED Blink code (blink.asm)

• Added PLD code to make a trigger on pin 17 when EPROM address 0xC000-0xF000 is written
• Code doesn't use any RAM (CPU and EPROM only)
• LED is on U2-15 to GNS w/ 1.8K resistor
• Assemble blink.asm code
• See Rev 2 checkout notes for LED
  • my path below, YMMV

..\..\M6809_Assembler\asm6809-2.13-w64\asm6809 blink.asm -H -l blink.lst -o blink.hex

• Works, blinks LED at about 2 Hz
• Can use this as a SRAM test outout
  • Fast blink = Fail
  • Slow blink = Pass

SRAM Test (ramLoop.asm)

• ramLoop.asm - GitHub
• Loops on SRAM write/read on LB-6809-01 card
• Turn on LED if the test passes
• Turn off LED if the test fails
• Passes

SRAM Test (ramTest1.asm)

• ramTest1.asm - GitHub
• Write/read SRAM write/read single location on LB-MEM-02 card
• Blink LED slowly if the test passes
• Blink LED quickly if the test fails
• Passes

SRAM Test (ramTest.asm)

• ramTest.asm - GitHub
• Write/read SRAM write/read on all SRAM on LB-MEM-02 card
  • Test single location with 0x55/0xaa
  • Test all RAM with ramp
    • Tests all locations but repeats ever 256 bytes so addresses are not completely tested
  • Ramp upper 7 address lines with a ramp
• Blink LED slowly if the test passes
• Blink LED quickly if the test fails
• Test takes 0.6 secs
• Passes

Reference Designs

• MP-09 MONITOR - SWTBUG SBUG monitor for the 6809
• SIMPLE-6809 Software - reference software that runs on SIMPLE-6809

Mechanicals

Rev 2

Checkout

Rev 2 Checkout

• Built
• Worked with NOP Tester
• Got 8 MHz crystal
• E signal is 2 MHz- good
• Add LED that can be written under program control
  • Add wire U1-31 to U2-11 (D0)
  • Add LEDSTR when strobe write to 0xC000-0xFFFF (U2-17)
  • Add LED to U2-15 with 1.8K resistor
  • Write to 0xF000 to toggle the line
    • Bit D0
  • Running blink.asm code

Rev 2 PCB Changes from Rev 1

• Add U1-34 to U2-7 (VPB/E)
• Eliminate oscillator
  • Add 8 MHz crystal/caps
  • Cheaper and easier to find
• Add 4.7K pullup to U1-40 (ABORT*/HALT) line
• Change resistor values to lighten up Iol
• Beef up power plane connections to J1 and CPU/cap
• Move reset switch to the top of the board (where the oscillator used to be)

Rev 1 Checkout Notes

• Did not build
• Add wire U1-34 to U2-7 (VPB/E)
• Ground XTAL pin on CPU U1-39 (to U1-1 = GND)
• Use BOM for resistor values, not silkscreen
• Add 4.7K pullup to ABORT* line

Assembly Sheet

Rev 2

• Interactive BOM

Rev 1

• Use BOM for resistor values, not silkscreen
• Interactive BOM