SIMPLE-6809

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Tindie-mediums.png

SIMPLE-6809 P1090253-720pxV.jpg

Features

Memory Map

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

Chipset

Design

CPU

SIMPLE-6809 U5 CPU.PNG

CPU Timing

MC6809 Timing.PNG

EEPROM

SIMPLE-6809 U4 EEPROM.PNG

SRAM

SIMPLE-6809 U2 SRAM.PNG

Logic ==============

SIMPLE-6809 U6 LOGIC.PNG

ACIA ==============

SIMPLE-6809 U3 ACIA.PNG

Headers / Connectors

SIMPLE-6809 REV1 CAD.PNG

J1 - RS-232 Serial

  • DB-9 Male
  • Pinout
  1. N/C
  2. Receive
  3. Transmit
  4. Loop to pin 6
  5. GND
  6. Loop to pin 4
  7. RTS
  8. N/C
  9. N/C

J2 / J5 - EPROM/EEPROM Select Jumpers

SIMPLE-6809 J2 J5.PNG

  • J2 - EPROM Pin 1 jumper
    • 1-2 for 28C64, 28C256 (Pull WE to VCC)
    • 2-3 for 27256, 27SF256, 27512 (Pull A14 to GND)
  • J5 - EPROM Pin 27 jumper
    • GND (2-3)

EEPROM Pin Table

27512 27256 27SF256 28C256 27128 2764 28C64 PIN PIN 2764 28C64 27128 28C256 27SF256 27256 27512
A15 VPP VPP A14 VPP VPP N/C 1 28 VCC VCC VCC VCC VCC VCC VCC
A12 A12 A12 A12 A12 A12 A12 2 27 PGM WE* PGM WE* A14 A14 A14
A7 A7 A7 A7 A7 A7 A7 3 26 A13 N/C A13 A13 A13 A13 A13
A6 A6 A6 A6 A6 A6 A6 4 25 A8 A8 A8 A8 A8 A8 A8
A5 A5 A5 A5 A5 A5 A5 5 24 A9 A9 A9 A9 A9 A9 A9
A4 A4 A4 A4 A4 A4 A4 6 23 A11 A11 A11 A11 A11 A11 A11
A3 A3 A3 A3 A3 A3 A3 7 22 OE* OE* OE* OE* OE* OE* OE*
A2 A2 A2 A2 A2 A2 A2 8 21 A10 A10 A10 A10 A10 A10 A10
A1 A1 A1 A1 A1 A1 A1 9 20 CE* CE* CE* CE* CE* CE* CE*
A0 A0 A0 A0 A0 A0 A0 10 19 D7 D7 D7 D7 D7 D7 D7
D0 D0 D0 D0 D0 D0 D0 11 18 D6 D6 D6 D6 D6 D6 D6
D1 D1 D1 D1 D1 D1 D1 12 17 D5 D5 D5 D5 D5 D5 D5
D2 D2 D2 D2 D2 D2 D2 13 16 D4 D4 D4 D4 D4 D4 D4
GND GND GND GND GND GND GND 14 15 D3 D3 D3 D3 D3 D3 D3

J3 - FTDI / TTL Serial

  • Requires a FTDI cross-over cable

SIMPLE-6809 J3 FTDI.PNG

  • Rev 1 PCB silkscreen is wrong (both sides of the card)

SIMPLE-6809 J3.PNG

  1. GND
  2. N/C
  3. +5V
  4. Transmit (out)
  5. Receive (in)
  6. N/C

J4 - 5V Power

  • 2x4 header

First Unit Checkout

SIMPLE-6809 P1090174-720PX.jpg

Install Sockets

  • Machined pin sockets

SIMPLE-6809 P1090171-720PX.jpg

Install Passives

Power

  • Install 2x4 at J4
  • Power card via J4 with 5V
  • Check power pins on parts

Clock

  • Install Clock parts
    • Install 7.3728 MHz crystal
    • Install C5, C6

SIMPLE-6809 P1090189-720px.jpg

  • Install CPU at U5

Reset

  • Install U7 Power Monitor
  • Install pushbutton switch SW1
  • Reset button gets stretched by Power Monitor U9
  • Measure reset at 68B09 U5 pin 37
  • Falling edge scope cap

EPROM

  • SST27C256 EEPROM
    • 32 KB part
    • Using first 16KB of EEPROM
    • J2 EEPROM pin 1 = VPP = VCC or GND
      • Jumper J2:2-3
    • J5 EEPROM pin 27 = A14 = GND
      • Jumper J5:2-3
  • U1 - Do not install MAX232


EEPROM Programming

  • Program using TL-866ii plus programmer
  • File = ExBasROM.hex
  • Set offsets for 27SF256 part
    • Part is 32 KB
    • hex files is 16 KB
  • Set From File Start Addr(Hex) to 0C000
  • To Buffer Start Addr(Hex) to 00000

SIMPLE-6809 Programmer Offsets.PNG

  • Memory Buffer should look like

SIMPLE-6809 Programmer BufferContents.PNG

  • Got Device ID error
  • Turn off ID check

SIMPLE-6502 TL866Plus Program.png

  • Device programmed/verified

Install CPU, ROM, RAM, ACIA

  • Do not install MAX232 yet

Test FTDI Serial

  • Silkscreen swapped for TX, RX

SIMPLE-6809 J3.PNG

SIMPLE-6809 BASIC DISPLAY.PNG

SIMPLE-6809 P1090253-720pxV.jpg

Test RS-232 Serial

  • With MAX232
  • Install DB-9 Male
  • Holes don't line up well, but 4-40 screws can fit
  • Connected to FTDI-49MM and DCE cards

FTDI DCE P1090192-720PXV.jpg

  • Works

Software

ROM BASIC assembly listing

  • AS9 was used to assemble the BASIC listing
  • Grant wrote a serial handler to control the text I/O, along with suitable Control-C break handling
  • Includes commands from the "Extended" BASIC ROM (from the "Extended BASIC Unraveled II" book)
  • The ROM in the SBC is fully working with all the commands in the Standard and Extended ROMS that are applicable to the SBC
  • Assembled using as9 (see link later on this page) with the following command...
as9 exbasrom.asm -now l s19
  • *-now" suppresses warnings
  • "l" produces a lst file
  • "s19" produces an s19 hex file
  • If you use as9, you will probably get a "Null pointer assignment" message when it completes
    • This can be ignored, and is a known bug with as9 that doesn't affect operation (according to the readme file that came with it)

Performance

  • TeraTerm settings

SIMPLE-6809 TeraTerm Setup.PNG

  • Test software
10 FOR I =1 TO 10000
20 PRINT I
30 NEXT I

  • Time ~52 secs

PCB Issues

Rev 2

  • Fix Silkscreen on J3 (see above J3 FTDI cable section)
  • Ordered 10 PCBs from JLCPCB

Rev 1

  • Works
  • Silkscreen J3 is wrong directions (TX/RX)

Mechanicals

SIMPLE-6809 REV1 MECHS.PNG

Assembly Sheet

Rev 2

Rev 1