Difference between revisions of "TinyPS2"
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** 1 mA @ 5V (without keyboard) | ** 1 mA @ 5V (without keyboard) | ||
** 13 mA @ 5V (including keyboard) | ** 13 mA @ 5V (including keyboard) | ||
+ | ** 8mA @ 3.3V (including keyboard) - requires a keyboard that works at 3.3V | ||
=== TinyPS2 === | === TinyPS2 === |
Revision as of 14:20, 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
Connectors
J1 - TTL Serial Connector
- 5V
- 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
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
- Scott has hex file
- FUSES = -U lfuse:w:0x62:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m
- Downloaded using TL866i
- 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?
TinyPS2V01 (Arduino UNO)
- Tried replacing Scott's code with "standard" Arduino code with a lot of issues
- First cut used libraries
- Resources (Arduino UNO)
Sketch uses 3334 bytes (10%) of program storage space. Maximum is 32256 bytes. Global variables use 377 bytes (18%) of dynamic memory, leaving 1671 bytes for local variables. Maximum is 2048 bytes.
- Issues "likely" due to single interrupt in ATTiny85
- Can't use Arduino libraries without conflict
- Both Arduino SoftSerial and PS/2 routines use this same interrupt
TinyPS2V02
- Read PS/2 keyboard, write Serial (9600 baud)
- PJRC PS/2 library
- Software Serial library
- Main sketch
- Didn't run when first tried
- Maybe PS2Keyboard library does not work on ATTiny85?
- Proper interrupt support for ATTiny85?
- Pin Change Interrupts on ATtiny85
- Verified KBD data, clocks are reaching ATTiny85
- Code
#include <SoftwareSerial.h> #include <PS2Keyboard.h> const int DataPin = 0; const int IRQpin = 1; #define rxPin 3 #define txPin 2 // Set up SoftwareSerial and PS/2 objects SoftwareSerial mySerial = SoftwareSerial(rxPin, txPin); PS2Keyboard keyboard; void setup() { pinMode(rxPin, INPUT); pinMode(txPin, OUTPUT); mySerial.begin(9600); keyboard.begin(DataPin, IRQpin); } void loop() { if (keyboard.available()) { // read the next key char c = keyboard.read(); mySerial.write(c); } }
- Resources (ATTiny85)
Sketch uses 3126 bytes (38%) of program storage space. Maximum is 8192 bytes. Global variables use 241 bytes (47%) of dynamic memory, leaving 271 bytes for local variables. Maximum is 512 bytes.
TinyPS2V03
- Test routine
- Sends out A-Z in serial line at 9600 baud (~100uS bit time)
- Software Serial library
- Verifies SoftwareSerial works
- Test with TinyPS04 sketch
- 2 mS off/on on serial output pin verifies delay(2)
- Caught missing bootloader (sets speed fuses)
- 2 mS off/on on serial output pin verifies delay(2)
TinyPS04
- Test with TinyPS04 sketch
- Toggle serial output line every 2 mS
- Verifies delay(2)
TinyPS05
- Intent: Verify interrupt from keyboard does not conflict with Software Serial
- Toggles serial out line if char comes in
- Never toggles
Programming Card
- 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
Other People's Videos
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