1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597
//! A platform agnostic driver to interface with the MAX7219 (LED matrix display driver)
//!
//! This driver was built using [`embedded-hal`] traits.
//!
//! [`embedded-hal`]: https://docs.rs/embedded-hal/~0.2
#![deny(unsafe_code)]
#![deny(warnings)]
#![no_std]
extern crate embedded_hal;
use embedded_hal::blocking::spi::Write;
use embedded_hal::digital::v2::OutputPin;
pub mod connectors;
use connectors::*;
/// Maximum number of displays connected in series supported by this lib.
const MAX_DISPLAYS: usize = 8;
/// Digits per display
const MAX_DIGITS: usize = 8;
/// Possible command register values on the display chip.
#[derive(Clone, Copy)]
pub enum Command {
Noop = 0x00,
Digit0 = 0x01,
Digit1 = 0x02,
Digit2 = 0x03,
Digit3 = 0x04,
Digit4 = 0x05,
Digit5 = 0x06,
Digit6 = 0x07,
Digit7 = 0x08,
DecodeMode = 0x09,
Intensity = 0x0A,
ScanLimit = 0x0B,
Power = 0x0C,
DisplayTest = 0x0F,
}
/// Decode modes for BCD encoded input.
#[derive(Copy, Clone)]
pub enum DecodeMode {
NoDecode = 0x00,
CodeBDigit0 = 0x01,
CodeBDigits3_0 = 0x0F,
CodeBDigits7_0 = 0xFF,
}
///
/// Error raised in case there was an error
/// during communication with the MAX7219 chip.
///
#[derive(Debug)]
pub enum DataError {
/// An error occurred when working with SPI
Spi,
/// An error occurred when working with a PIN
Pin,
}
///
/// Handles communication with the MAX7219
/// chip for segmented displays. Each display can be
/// connected in series with another and controlled via
/// a single connection. The actual connection interface
/// is selected via constructor functions.
///
pub struct MAX7219<CONNECTOR> {
c: CONNECTOR,
decode_mode: DecodeMode,
}
impl<CONNECTOR> MAX7219<CONNECTOR>
where
CONNECTOR: Connector,
{
///
/// Powers on all connected displays
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn power_on(&mut self) -> Result<(), DataError> {
for i in 0..self.c.devices() {
self.c.write_data(i, Command::Power, 0x01)?;
}
Ok(())
}
///
/// Powers off all connected displays
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn power_off(&mut self) -> Result<(), DataError> {
for i in 0..self.c.devices() {
self.c.write_data(i, Command::Power, 0x00)?;
}
Ok(())
}
///
/// Clears display by settings all digits to empty
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn clear_display(&mut self, addr: usize) -> Result<(), DataError> {
for i in 1..9 {
self.c.write_raw(addr, i, 0x00)?;
}
Ok(())
}
///
/// Sets intensity level on the display
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
/// * `intensity` - intensity value to set to `0x00` to 0x0F`
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn set_intensity(&mut self, addr: usize, intensity: u8) -> Result<(), DataError> {
self.c.write_data(addr, Command::Intensity, intensity)
}
///
/// Sets decode mode to be used on input sent to the display chip.
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
/// * `mode` - the decode mode to set
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn set_decode_mode(&mut self, addr: usize, mode: DecodeMode) -> Result<(), DataError> {
self.decode_mode = mode; // store what we set
self.c.write_data(addr, Command::DecodeMode, mode as u8)
}
///
/// Writes byte string to the display
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
/// * `string` - the byte string to send 8 bytes long. Unknown characters result in question mark.
/// * `dots` - u8 bit array specifying where to put dots in the string (1 = dot, 0 = not)
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn write_str(
&mut self,
addr: usize,
string: &[u8; MAX_DIGITS],
dots: u8,
) -> Result<(), DataError> {
let prev_dm = self.decode_mode;
self.set_decode_mode(0, DecodeMode::NoDecode)?;
let mut digit: u8 = MAX_DIGITS as u8;
let mut dot_product: u8 = 0b1000_0000;
for b in string {
let dot = (dots & dot_product) > 0;
dot_product >>= 1;
self.c.write_raw(addr, digit, ssb_byte(*b, dot))?;
digit -= 1;
}
self.set_decode_mode(0, prev_dm)?;
Ok(())
}
///
/// Writes BCD encoded string to the display
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
/// * `bcd` - the bcd encoded string slice consisting of [0-9,-,E,L,H,P]
/// where upper case input for alphabetic characters results in dot being set.
/// Length of string is always 8 bytes, use spaces for blanking.
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn write_bcd(&mut self, addr: usize, bcd: &[u8; MAX_DIGITS]) -> Result<(), DataError> {
let prev_dm = self.decode_mode;
self.set_decode_mode(0, DecodeMode::CodeBDigits7_0)?;
let mut digit: u8 = MAX_DIGITS as u8;
for b in bcd {
self.c.write_raw(addr, digit, bcd_byte(*b))?;
digit -= 1;
}
self.set_decode_mode(0, prev_dm)?;
Ok(())
}
///
/// Writes a right justified integer with sign
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
/// * `val` - an integer i32
///
/// # Errors
///
/// * `DataError` - returned in case there was an integer over flow
///
pub fn write_integer(&mut self, addr: usize, value: i32) -> Result<(), DataError> {
let mut buf = [0u8; 8];
let j = base_10_bytes(value, &mut buf);
buf = pad_left(j);
self.write_str(addr, &mut buf, 0b00000000)?;
Ok(())
}
///
/// Writes a right justified hex formatted integer with sign
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
/// * `val` - an integer i32
///
/// # Errors
///
/// * `DataError` - returned in case there was an integer over flow
///
pub fn write_hex(&mut self, addr: usize, value: u32) -> Result<(), DataError> {
let mut buf = [0u8; 8];
let j = hex_bytes(value, &mut buf);
buf = pad_left(j);
self.write_str(addr, &mut buf, 0b00000000)?;
Ok(())
}
///
/// Writes a raw value to the display
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
/// * `raw` - an array of raw bytes to write. Each bit represents a pixel on the display
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn write_raw(&mut self, addr: usize, raw: &[u8; MAX_DIGITS]) -> Result<(), DataError> {
let prev_dm = self.decode_mode;
self.set_decode_mode(0, DecodeMode::NoDecode)?;
let mut digit: u8 = 1;
for b in raw {
self.write_raw_byte(addr, digit, *b)?;
digit += 1;
}
self.set_decode_mode(0, prev_dm)?;
Ok(())
}
///
/// Writes a single byte to the underlying display. This method is very
/// low-level: most users will prefer to use one of the other `write_*`
/// methods.
///
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
/// * `header` - the register to write the value to
/// * `data` - the value to write
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn write_raw_byte(&mut self, addr: usize, header: u8, data: u8) -> Result<(), DataError> {
self.c.write_raw(addr, header, data)
}
///
/// Set test mode on/off
///
/// # Arguments
///
/// * `addr` - display to address as connected in series (0 -> last)
/// * `is_on` - whether to turn test mode on or off
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn test(&mut self, addr: usize, is_on: bool) -> Result<(), DataError> {
if is_on {
self.c.write_data(addr, Command::DisplayTest, 0x01)
} else {
self.c.write_data(addr, Command::DisplayTest, 0x00)
}
}
// internal constructor, users should call ::from_pins or ::from_spi
fn new(connector: CONNECTOR) -> Result<Self, DataError> {
let mut max7219 = MAX7219 {
c: connector,
decode_mode: DecodeMode::NoDecode,
};
max7219.init()?;
Ok(max7219)
}
fn init(&mut self) -> Result<(), DataError> {
for i in 0..self.c.devices() {
self.test(i, false)?; // turn testmode off
self.c.write_data(i, Command::ScanLimit, 0x07)?; // set scanlimit
self.set_decode_mode(i, DecodeMode::NoDecode)?; // direct decode
self.clear_display(i)?; // clear all digits
}
self.power_off()?; // power off
Ok(())
}
}
impl<DATA, CS, SCK> MAX7219<PinConnector<DATA, CS, SCK>>
where
DATA: OutputPin,
CS: OutputPin,
SCK: OutputPin,
{
///
/// Construct a new MAX7219 driver instance from DATA, CS and SCK pins.
///
/// # Arguments
///
/// * `displays` - number of displays connected in series
/// * `data` - the MOSI/DATA PIN used to send data through to the display set to output mode
/// * `cs` - the CS PIN used to LOAD register on the display set to output mode
/// * `sck` - the SCK clock PIN used to drive the clock set to output mode
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn from_pins(displays: usize, data: DATA, cs: CS, sck: SCK) -> Result<Self, DataError> {
MAX7219::new(PinConnector::new(displays, data, cs, sck))
}
}
impl<SPI> MAX7219<SpiConnector<SPI>>
where
SPI: Write<u8>,
{
///
/// Construct a new MAX7219 driver instance from pre-existing SPI in full hardware mode.
/// The SPI will control CS (LOAD) line according to it's internal mode set.
/// If you need the CS line to be controlled manually use MAX7219::from_spi_cs
///
/// * `NOTE` - make sure the SPI is initialized in MODE_0 with max 10 Mhz frequency.
///
/// # Arguments
///
/// * `displays` - number of displays connected in series
/// * `spi` - the SPI interface initialized with MOSI, MISO(unused) and CLK
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn from_spi(displays: usize, spi: SPI) -> Result<Self, DataError> {
MAX7219::new(SpiConnector::new(displays, spi))
}
}
impl<SPI, CS> MAX7219<SpiConnectorSW<SPI, CS>>
where
SPI: Write<u8>,
CS: OutputPin,
{
///
/// Construct a new MAX7219 driver instance from pre-existing SPI and CS pin
/// set to output. This version of the connection uses the CS pin manually
/// to avoid issues with how the CS mode is handled in hardware SPI implementations.
///
/// * `NOTE` - make sure the SPI is initialized in MODE_0 with max 10 Mhz frequency.
///
/// # Arguments
///
/// * `displays` - number of displays connected in series
/// * `spi` - the SPI interface initialized with MOSI, MISO(unused) and CLK
/// * `cs` - the CS PIN used to LOAD register on the display set to output mode
///
/// # Errors
///
/// * `DataError` - returned in case there was an error during data transfer
///
pub fn from_spi_cs(displays: usize, spi: SPI, cs: CS) -> Result<Self, DataError> {
MAX7219::new(SpiConnectorSW::new(displays, spi, cs))
}
}
///
/// Translate alphanumeric ASCII bytes into BCD
/// encoded bytes expected by the display chip.
///
fn bcd_byte(b: u8) -> u8 {
match b as char {
' ' => 0b0000_1111, // "blank"
'-' => 0b0000_1010, // - without .
'e' => 0b0000_1011, // E without .
'E' => 0b1000_1011, // E with .
'h' => 0b0000_1100, // H without .
'H' => 0b1000_1100, // H with .
'l' => 0b0000_1101, // L without .
'L' => 0b1000_1101, // L with .
'p' => 0b0000_1110, // L without .
'P' => 0b1000_1110, // L with .
_ => b,
}
}
///
/// Translate alphanumeric ASCII bytes into segment set bytes
///
fn ssb_byte(b: u8, dot: bool) -> u8 {
let mut result = match b as char {
' ' => 0b0000_0000, // "blank"
'.' => 0b1000_0000,
'-' => 0b0000_0001, // -
'_' => 0b0000_1000, // _
'0' => 0b0111_1110,
'1' => 0b0011_0000,
'2' => 0b0110_1101,
'3' => 0b0111_1001,
'4' => 0b0011_0011,
'5' => 0b0101_1011,
'6' => 0b0101_1111,
'7' => 0b0111_0000,
'8' => 0b0111_1111,
'9' => 0b0111_1011,
'a' | 'A' => 0b0111_0111,
'b' => 0b0001_1111,
'c' | 'C' => 0b0100_1110,
'd' => 0b0011_1101,
'e' | 'E' => 0b0100_1111,
'f' | 'F' => 0b0100_0111,
'g' | 'G' => 0b0101_1110,
'h' | 'H' => 0b0011_0111,
'i' | 'I' => 0b0011_0000,
'j' | 'J' => 0b0011_1100,
// K undoable
'l' | 'L' => 0b0000_1110,
// M undoable
'n' | 'N' => 0b0001_0101,
'o' | 'O' => 0b0111_1110,
'p' | 'P' => 0b0110_0111,
'q' => 0b0111_0011,
// R undoable
's' | 'S' => 0b0101_1011,
// T undoable
'u' | 'U' => 0b0011_1110,
// V undoable
// W undoable
// X undoable
// Y undoable
// Z undoable
_ => 0b1110_0101, // ?
};
if dot {
result |= 0b1000_0000; // turn "." on
}
result
}
///
/// Convert the integer into an integer byte Sequence
///
fn base_10_bytes(mut n: i32, buf: &mut [u8]) -> &[u8] {
let mut sign: bool = false;
//don't overflow the display
if (n > 99999999) || (n < -9999999) {
return b"Err";
}
if n == 0 {
return b"0";
}
if n < 0 {
n = -n;
sign = true;
}
let mut i = 0;
while n > 0 {
buf[i] = (n % 10) as u8 + b'0';
n /= 10;
i += 1;
}
if sign {
buf[i] = b'-';
i += 1;
}
let slice = &mut buf[..i];
slice.reverse();
&*slice
}
//
/// Convert the integer into a hexidecimal byte Sequence
///
fn hex_bytes(mut n: u32 , buf: &mut [u8]) -> &[u8] {
// don't overflow the display ( 0xFFFFFFF)
if n == 0 {
return b"0";
}
let mut i = 0;
while n > 0 {
let digit = (n % 16) as u8;
buf[i] = match digit {
0 => b'0',
1 => b'1',
2 => b'2',
3 => b'3',
4 => b'4',
5 => b'5',
6 => b'6',
7 => b'7',
8 => b'8',
9 => b'9',
10 => b'a',
11 => b'b',
12 => b'c',
13 => b'd',
14 => b'e',
15 => b'f',
_ => b'?',
};
n /= 16;
i += 1;
}
let slice = &mut buf[..i];
slice.reverse();
&*slice
}
///
/// Take a byte slice and pad the left hand side
///
fn pad_left(val: &[u8]) -> [u8; 8] {
assert!(val.len() <= 8);
let size: usize = 8;
let pos: usize = val.len();
let mut cur: usize = 1;
let mut out: [u8; 8] = *b" ";
while cur <= pos {
out[size - cur] = val[pos - cur];
cur += 1;
}
out
}