Difference between revisions of "TinyPS2"
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* [[ATProgHead]] | * [[ATProgHead]] | ||
** Running Arduino as ISP | ** Running Arduino as ISP | ||
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== Schematic == | == Schematic == |
Revision as of 15:10, 5 May 2022
Contents
Features
- PS/2 keyboard or mouse to TTL Level Serial converter based on Scott Baker BLOG
- ATTiny85 8-bit CPU
- Run at 8 MHz in this use-case
- 8 KB of In System Programmable (ISP) flash
- 8-MHz internal RC oscillator that can be used as the default clock
- 512 bytes of EEPROM
- 512 bytes of SRAM
- 115,200 baud
- 49x49mm ODAS form factor
- 4-40 mounting holes
- 3.3V or 5V operation
- Current measurement
- 1 mA @ 5V (without keyboard)
- 13 mA @ 5V (including keyboard)
- 8mA @ 3.3V (including keyboard)
- Requires a keyboard that works at 3.3V
TinyPS2 Connections
Connectors
J1 - TTL Serial Connector
- VCC (pin nearest to J1 silkscreem)
- SERTX
- N/C
- GND
J2 - PS/2
- Standard PS/2 Mini-DIN-6 connector
H2 - In-System Programming Header
- SPI connector to download ATTiny85
- 2x3 header
- Program ATTiny85 without PS/2 keyboard attached
- Pinout
- KBCLK
- VCC
- SERTX
- KBDAT
- RST*
- GND
Firmware Builds
- Scott Baker's build
- Arduino IDE port
Scott Baker's build
- Scott's GitHub page
- Scott appears to have used Crosspack for AVR software development
- Scott uses two libraries from other projects
- ATTiny85 UART Library - The Garage Lab
- Interrupts: Interfacing a Microcontroller with a PS/2 Keyboard - PS/2 Keyboard Library
Programming Scott's Build
- Used TL866ii Plus Programmer
- Scott has serkey.hex file
- FUSES = -U lfuse:w:0x62:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m
- Used Fuse bits from Programmer
- Matched lfuse values already
Tested Scott's Build
- Works really well
- 115,200 baud
- Works at 3.3V or 5V
- Drops out around 3.15V - may need BOD bit changed?
TinyPS2 (Arduino IDE)
- Converted Scott Baker's build to the Arduino IDE
- Move main init code to setup()
- Move main inner loop to loop()
- GitHub Software Repo
- Resources (Arduino UNO)
Sketch uses 850 bytes (10%) of program storage space. Maximum is 8192 bytes. Global variables use 15 bytes (2%) of dynamic memory, leaving 497 bytes for local variables. Maximum is 512 bytes.
Programming Card (Arduino IDE)
- Programming procedure is taken from here
- Add ATTiny Board support to Preferences, Path:
https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json
- Select ATTiny85, 8 Mhz
- Burn bootloader - Otherwise clock is way off
- ATProgHead
- Running Arduino as ISP
Schematic
Issues
- Missing pull-up resistors on PS/2
- Rev 2 - add pull-up resistors
- (There's pullups in the part so this may not be needed)
- Missing C3 cap in sequence
- Rev 2 - change C4 => C3