From 9d678fbace2e4931e39ab5b95b2ec7493a18f549 Mon Sep 17 00:00:00 2001 From: Blaise Thompson Date: Mon, 25 Jan 2021 12:15:05 -0600 Subject: digital-driver readme --- .../attiny85_i2c_slave_task.ino | 246 +++++++++++++++++++++ 1 file changed, 246 insertions(+) create mode 100644 digital-driver/firmware/TinyWireS/examples/attiny85_i2c_slave_task/attiny85_i2c_slave_task.ino (limited to 'digital-driver/firmware/TinyWireS/examples/attiny85_i2c_slave_task/attiny85_i2c_slave_task.ino') diff --git a/digital-driver/firmware/TinyWireS/examples/attiny85_i2c_slave_task/attiny85_i2c_slave_task.ino b/digital-driver/firmware/TinyWireS/examples/attiny85_i2c_slave_task/attiny85_i2c_slave_task.ino new file mode 100644 index 0000000..4b3f269 --- /dev/null +++ b/digital-driver/firmware/TinyWireS/examples/attiny85_i2c_slave_task/attiny85_i2c_slave_task.ino @@ -0,0 +1,246 @@ +/** + * Example sketch for writing to and reading from a slave in transactional manner, it will also blink a led attached to pin 3 (which is the SOIC pin 2) + * (provided you're using one of my ATTiny85 boards from https://github.com/rambo/attiny_boards with the led soldered) + * + * NOTE: You must not use delay() or I2C communications will fail, use tws_delay() instead (or preferably some smarter timing system, like the Task library used in this example) + * + * On write the first byte received is considered the register addres to modify/read + * On each byte sent or read the register address is incremented (and it will loop back to 0) + * + * You can try this with the Arduino I2C REPL sketch at https://github.com/rambo/I2C/blob/master/examples/i2crepl/i2crepl.ino + * If you have bus-pirate remember that the older revisions do not like the slave streching the clock, this leads to all sorts of weird behaviour + * + * By default this blinks the SOS morse pattern and then has long on/off time to indicate end of pattern, send [ 8 0 32 ] (using the REPL/bus-pirate + * semantics) to make the delay per bit smaller (and thus blinking faster). The pattern lenght is calculated from the register size, it would be fairly + * trivial to make it yet another variable changeable via I2C. + * + * You need to have at least 8MHz clock on the ATTiny for this to work (and in fact I have so far tested it only on ATTiny85 @8MHz using internal oscillator) + * Remember to "Burn bootloader" to make sure your chip is in correct mode + */ + + +/** + * Pin notes by Suovula, see also http://hlt.media.mit.edu/?p=1229 + * + * DIP and SOIC have same pinout, however the SOIC chips are much cheaper, especially if you buy more than 5 at a time + * For nice breakout boards see https://github.com/rambo/attiny_boards + * + * Basically the arduino pin numbers map directly to the PORTB bit numbers. + * +// I2C +arduino pin 0 = not(OC1A) = PORTB <- _BV(0) = SOIC pin 5 (I2C SDA, PWM) +arduino pin 2 = = PORTB <- _BV(2) = SOIC pin 7 (I2C SCL, Analog 1) +// Timer1 -> PWM +arduino pin 1 = OC1A = PORTB <- _BV(1) = SOIC pin 6 (PWM) +arduino pin 3 = not(OC1B) = PORTB <- _BV(3) = SOIC pin 2 (Analog 3) +arduino pin 4 = OC1B = PORTB <- _BV(4) = SOIC pin 3 (Analog 2) + */ +#define I2C_SLAVE_ADDRESS 0x4 // the 7-bit address (remember to change this when adapting this example) +// Get this from https://github.com/rambo/TinyWire +#include +// The default buffer size, Can't recall the scope of defines right now +#ifndef TWI_RX_BUFFER_SIZE +#define TWI_RX_BUFFER_SIZE ( 16 ) +#endif +// Get this library from http://bleaklow.com/files/2010/Task.tar.gz +// and read http://bleaklow.com/2010/07/20/a_very_simple_arduino_task_manager.html for background and instructions +#include +#include + +// The led is connected so that the tiny sinks current +#define LED_ON LOW +#define LED_OFF HIGH + +// The I2C registers +volatile uint8_t i2c_regs[] = +{ + 150, // Delay between each position (ms, remeber that this isa byte so 255 is max) + B10101000, // SOS pattern + B01110111, + B01110001, + B01010000, + B00000000, + B11111111, // Long on and off to mark end of pattern + B00000000, +}; +// Tracks the current register pointer position +volatile byte reg_position; +const byte reg_size = sizeof(i2c_regs); + + +/** + * BEGIN: PatternBlinker task based on the Task library Blinker example + */ +// Timed task to blink a LED. +const byte pattern_lenght = (sizeof(i2c_regs)-1) * 8; // bits (first is the speed, rest is the pattern) +class PatternBlinker : public TimedTask +{ +public: + // Create a new blinker for the specified pin and rate. + PatternBlinker(uint8_t _pin); + virtual void run(uint32_t now); +private: + uint8_t pin; // LED pin. + uint8_t pattern_position; // Used to calcuate the register and bit offset +}; + +PatternBlinker::PatternBlinker(uint8_t _pin) +: TimedTask(millis()), + pin(_pin) +{ + pinMode(pin, OUTPUT); // Set pin for output. +} + +void PatternBlinker::run(uint32_t now) +{ + // Start by setting the next runtime + incRunTime(i2c_regs[0]); + + // Written out for clear code, the complier might optimize it to something more efficient even without it being unrolled into one line + byte reg = i2c_regs[1+(pattern_position/8)]; // Get the register where the bit pattern position is stored + byte shift_amount = 7 - (pattern_position % 7); // To have "natural" left-to-right pattern flow. + bool state = (reg >> shift_amount) & 0x1; + if (state) { + digitalWrite(pin, LED_ON); + } else { + digitalWrite(pin, LED_OFF); + } + // Calculate the next pattern position + pattern_position = (pattern_position+1) % pattern_lenght; +} +/** + * END: PatternBlinker task copied from the Task library example + */ +/** + * BEGIN: I2C Stop flag checker + * + * This task needs to run almost all the time due to the USI I2C implementation limitations + * + * So I2CStopCheck_YIELD_TICKS below is used to specify how often the task is run, not it's every 4 ticks + */ +#define I2CStopCheck_YIELD_TICKS 4 +class I2CStopCheck : public Task +{ +public: + I2CStopCheck(); + virtual void run(uint32_t now); + virtual bool canRun(uint32_t now); +private: + uint8_t yield_counter; // Incremented on each canRun call, used to yield to other tasks. +}; + +I2CStopCheck::I2CStopCheck() +: Task() +{ +} + +// We can't just return true since then no other task could ever run (since we have the priority) +bool I2CStopCheck::canRun(uint32_t now) +{ + yield_counter++; + bool ret = false; + if (yield_counter == I2CStopCheck_YIELD_TICKS) + { + ret = true; + yield_counter = 0; + } + return ret; +} + +void I2CStopCheck::run(uint32_t now) +{ + TinyWireS_stop_check(); +} +/** + * END: I2C Stop flag checker + */ + +// Create the tasks. +PatternBlinker blinker(3); +I2CStopCheck checker; + +// Tasks are in priority order, only one task is run per tick +Task *tasks[] = { &checker, &blinker, }; +TaskScheduler sched(tasks, NUM_TASKS(tasks)); + + +/** + * This is called for each read request we receive, never put more than one byte of data (with TinyWireS.send) to the + * send-buffer when using this callback + */ +void requestEvent() +{ + TinyWireS.send(i2c_regs[reg_position]); + // Increment the reg position on each read, and loop back to zero + reg_position++; + if (reg_position >= reg_size) + { + reg_position = 0; + } +} + +/** + * The I2C data received -handler + * + * This needs to complete before the next incoming transaction (start, data, restart/stop) on the bus does + * so be quick, set flags for long running tasks to be called from the mainloop instead of running them directly, + */ +void receiveEvent(uint8_t howMany) +{ + if (howMany < 1) + { + // Sanity-check + return; + } + if (howMany > TWI_RX_BUFFER_SIZE) + { + // Also insane number + return; + } + + reg_position = TinyWireS.receive(); + howMany--; + if (!howMany) + { + // This write was only to set the buffer for next read + return; + } + while(howMany--) + { + i2c_regs[reg_position] = TinyWireS.receive(); + reg_position++; + if (reg_position >= reg_size) + { + reg_position = 0; + } + } +} + + +void setup() +{ + // TODO: Tri-state this and wait for input voltage to stabilize + pinMode(3, OUTPUT); // OC1B-, Arduino pin 3, ADC + digitalWrite(3, LED_ON); // Note that this makes the led turn on, it's wire this way to allow for the voltage sensing above. + + pinMode(1, OUTPUT); // OC1A, also The only HW-PWM -pin supported by the tiny core analogWrite + + /** + * Reminder: taking care of pull-ups is the masters job + */ + + TinyWireS.begin(I2C_SLAVE_ADDRESS); + TinyWireS.onReceive(receiveEvent); + TinyWireS.onRequest(requestEvent); + + + // Whatever other setup routines ? + + digitalWrite(3, LED_OFF); +} + +void loop() +{ + // Run the scheduler - never returns. + sched.run(); +} -- cgit v1.2.3