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// MIT License
//
// Copyright (c) 2022 Philipp Schuster <phip1611@gmail.com>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#![no_std]
#![deny(
clippy::all,
clippy::cargo,
clippy::nursery,
// clippy::restriction,
// clippy::pedantic
)]
// now allow a few rules which are denied by the above statement
// --> they are ridiculous and not necessary
#![allow(
clippy::fallible_impl_from,
clippy::needless_doctest_main,
clippy::redundant_pub_crate,
clippy::suboptimal_flops
)]
#![deny(missing_docs)]
#![deny(missing_debug_implementations)]
#![deny(rustdoc::all)]
// Inspired by / Special thanks to:
// https://github.com/avishorp/TM1637
//! Generic GPIO driver for TM1637.
//! With this driver you can control for example the 4-digit 7-segment display from AZ-Delivery.
//! This is not dependent on a specific GPIO library.
//! This library was tested on a Raspberry Pi with its GPIO interface.
//! Feel free to contribute. :)
// from rust core library; no "external crate" in the manner that this is no crates.io dependency;
// needed because no_std
#[macro_use] // wee need the !format macro
extern crate alloc;
// Import our enums/arrays for the symbol mappings to the 7 segment display
#[cfg(feature = "fourdigit7segdis")]
pub mod fourdigit7segdis;
pub mod mappings;
// provides conditionally bindings to specific GPIO interfaces; can be activated via cargo features
pub mod gpio_api;
// to use Box: we don't have std::prelude here
use crate::mappings::{LoCharBits, NumCharBits, SpecialCharBits, UpCharBits};
use alloc::boxed::Box;
use alloc::vec::Vec;
use core::fmt::{Debug, Formatter};
// A
// ---
// F | | B
// -G-
// E | | C
// ---
// D
/// According to the data sheet the TM1637 can address 6 display registers.
/// Note that not all devices using it do as well. For example the 4-digit
/// 7-segment display from AzDelivery only uses 4.
pub const DISPLAY_REGISTERS_COUNT: usize = 6;
/// The value of a GPIO pin.
#[repr(u8)]
#[derive(Clone, Copy, Debug)]
pub enum GpioPinValue {
/// Low.
LOW,
/// High.
HIGH,
}
impl From<u8> for GpioPinValue {
fn from(x: u8) -> Self {
if x == 0 {
Self::LOW
} else {
Self::HIGH
}
}
}
/// Adapter between your code and the TM1637 via GPIO interface.
/// You can use the GPIO interface/library that you want. Just provide
/// the corresponding "glue" functions so that this adapter can access GPIO.
///
/// Be wise when you choose a value for `bit_delay_us`. This delay is important
/// to ensure that changed signals are actually on the pins. My experience showed
/// that 100 (µs) is a safe value on the Raspberry Pi.
pub struct TM1637Adapter {
/// Function that writes the value on the GPIO pin that acts as the clock.
pin_clock_write_fn: Box<dyn Fn(GpioPinValue)>,
/// Function that writes the value on the GPIO pin that acts as data in and out.
pin_dio_write_fn: Box<dyn Fn(GpioPinValue)>,
/// Function that reads from the data in and out pin.
pin_dio_read_fn: Box<dyn Fn() -> GpioPinValue>,
/// Delay function after data bits and clock bits have been set. This may be necessary
/// on some hardware.
bit_delay_fn: Box<dyn Fn()>,
/// Representation of the display state in bits for the TM1637.
/// Bits 7-4 are zero. Later the "display control"-command prefix will be there.
/// Bits 3-0 are for display on/off and brightness.
brightness: u8,
}
impl Debug for TM1637Adapter {
fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
f.debug_struct("TM1637Adapter")
// cast to pointer: print as hex
.field("brightness", &(self.brightness as *const u8))
.field("pin_clock_write_fn", &"<func>")
.field("pin_dio_write_fn", &"<func>")
.field("pin_dio_read_fn", &"<func>")
.field("bit_delay_fn", &"<func>")
.finish()
}
}
/// The level of brightness.
/// The TM1637 "DisplayControl"-command transports the brightness information
/// in bits 0 to 2.
#[repr(u8)]
#[derive(Debug)]
pub enum Brightness {
/// Brightness level 0. Lowest brightness.
L0 = 0b000,
/// Brightness level 1.
L1 = 0b001,
/// Brightness level 2.
L2 = 0b010,
/// Brightness level 3.
L3 = 0b011,
/// Brightness level 4.
L4 = 0b100,
/// Brightness level 5.
L5 = 0b101,
/// Brightness level 6.
L6 = 0b110,
/// Brightness level 7. Highest brightness.
L7 = 0b111,
}
/// Whether the display is on or off.
/// The TM1637 "DisplayControl"-command transports the display on/off information
/// in the third bit (2^3) of the command.
#[repr(u8)]
#[derive(Debug)]
pub enum DisplayState {
/// Display off.
OFF = 0b0000,
/// Display On.
ON = 0b1000,
}
/// The "ISA"/Commands of the TM1637. See data sheet
/// for more information. This is only a subset of the possible values.
#[repr(u8)]
#[derive(Debug)]
pub enum ISA {
/// Start instruction. "write data to display register"-mode.
DataCommandWriteToDisplay = 0b0100_0000,
/// Base command for the display address. Bits 2-0 specify the display (0-5).
/// If not deactivated, the device does an internal increment of ths display address
/// as bytes are written.
AddressCommandBase = 0b1100_0000,
/// Base Command for writing to the display. Needs to be ORed with [`Brightness`] and
/// [`DisplayState`]. The base command alone set's the display off.
/// Bit 3 tells if the display is one. Bits 0-2 tell the brightness.
DisplayCommandBase = 0b1000_0000,
}
impl TM1637Adapter {
/// Creates a new object to interact via GPIO with a TM1637.
/// Activates the display and set's the brightness to the highest value.
///
/// * `pin_clock_write_fn` function to write bit to CLK pin
/// * `pin_dio_write_fn` function to write bit to DIO pin
/// * `pin_dio_read_fn` function to read value from DIO pin
/// * `bit_delay_fn` function that is invoked after a bit has been written to a pin.
/// It depends on your hardware and your GPIO driver. Sometimes 0 is even fine.
pub fn new(
pin_clock_write_fn: Box<dyn Fn(GpioPinValue)>,
pin_dio_write_fn: Box<dyn Fn(GpioPinValue)>,
pin_dio_read_fn: Box<dyn Fn() -> GpioPinValue>,
bit_delay_fn: Box<dyn Fn()>,
) -> Self {
// assume both are already output pins - this is the contract that needs to be fulfilled!
(pin_clock_write_fn)(GpioPinValue::LOW);
(pin_dio_write_fn)(GpioPinValue::LOW);
Self {
pin_clock_write_fn,
pin_dio_write_fn,
pin_dio_read_fn,
bit_delay_fn,
brightness: DisplayState::ON as u8 | Brightness::L7 as u8,
}
}
/// Sets the display state. The display state is the 3rd bit of the
/// "display control"-command.
/// This setting is not committed until a write operation has been made.
pub fn set_display_state(&mut self, ds: DisplayState) {
// keep old state for brightness
let old_brightness = self.brightness & 0b0000_0111;
// take 3rd bit (the one that says display on/off) into the new value
self.brightness = ds as u8 | old_brightness;
}
/// Sets the brightness of the screen. The brightness are the lower
/// 3 bits of the "display control"-command.
/// This setting is not committed until a write operation has been made.
pub fn set_brightness(&mut self, brightness: Brightness) {
// look if display is configured as on
let display_on = self.brightness as u8 & DisplayState::ON as u8;
self.brightness = display_on | brightness as u8;
}
/// Writes all raw segments data beginning at the position into the display registers.
/// It uses auto increment internally to write into all further registers.
/// This functions does an internal check so that not more than 6 registers can be
/// addressed/written.
/// * `segments` Raw data describing the bits of the 7 segment display.
/// * `n` Length of segments array.
/// * `pos` The start position of the display register. While bytes are
/// written, address is adjusted internally via auto increment.
/// Usually this is 0, if you want to write data to all 7 segment
/// displays.
pub fn write_segments_raw(&self, segments: &[u8], pos: u8) {
let mut n = segments.len() as u8;
// beeing a little bit more failure tolerant
if n == 0 {
return;
} // nothing to do
let pos = pos % DISPLAY_REGISTERS_COUNT as u8; // only valid positions/registers
// valid values are
// n = 1, pos = {0, 1, 2, 3, 4, 5}
// n = 2, pos = {0, 1, 2, 3, 4}
// n = 3, pos = {0, 1, 2, 3}
// n = 4, pos = {0, 1, 2}
// n = 5, pos = {0, 1}
// n = 6, pos = {0}
// => n + pos must be <= DISPLAY_REGISTERS_COUNT
if n + pos > DISPLAY_REGISTERS_COUNT as u8 {
// only write as much data as registers are available
n = DISPLAY_REGISTERS_COUNT as u8 - pos;
}
// Command 1 / 2
// for more information about this flow: see data sheet / specification of TM1637
// or AZDelivery's 7 segment display
self.start();
self.write_byte_and_wait_ack(ISA::DataCommandWriteToDisplay as u8);
self.stop();
// Command 2
self.start();
self.write_byte_and_wait_ack(ISA::AddressCommandBase as u8 | (pos & 0x3));
// Write the remaining data bytes
// TM1637 does auto increment internally
for i in 0..n {
self.write_byte_and_wait_ack(segments[i as usize]);
}
self.stop();
// we do this everytime because it will be a common flow that people write something
// and expect the display to be on
self.write_display_state();
}
/// This uses fixed address mode (see data sheet) internally to write data to
/// a specific position of the display.
/// Position is 0, 1, 2, or 3.
pub fn write_segment_raw(&self, segments: u8, position: u8) {
self.write_segments_raw(&[segments], position)
}
/// Send command that sets the display state on the micro controller.
pub fn write_display_state(&self) {
self.start();
// bits 0-2 brightness; bit 3 is on/off
self.write_byte_and_wait_ack(ISA::DisplayCommandBase as u8 | self.brightness);
self.stop();
}
/// Clears the display.
pub fn clear(&self) {
// begin at position 0 and write 0 into display registers 0 to 5
self.write_segments_raw(&[0, 0, 0, 0, 0, 0], 0);
}
/// Writes a byte bit by bit and waits for the acknowledge.
fn write_byte_and_wait_ack(&self, byte: u8) {
let mut data = byte;
// 8 bits
for _ in 0..8 {
// CLK low
(self.pin_clock_write_fn)(GpioPinValue::LOW);
// Set data bit (we send one bit of our byte per iteration)
// LSF (least significant bit) first
// => target device uses a shift register => this way the byte has the
// correct order on the target
(self.pin_dio_write_fn)(GpioPinValue::from(data & 0x01));
self.bit_delay();
// CLK high
(self.pin_clock_write_fn)(GpioPinValue::HIGH);
self.bit_delay();
// shift to next bit
data >>= 1;
}
self.recv_ack();
}
/// Encodes a number from 0 to 9999 on the display.
pub fn encode_number(num: u16) -> [u8; 4] {
let mut num = num % 10000;
let mut bits: [u8; 4] = [0; 4];
for i in 0..4 {
let digit = (num % 10) as u8;
bits[3 - i] = Self::encode_digit(digit);
num /= 10;
}
bits
}
/// Encodes a number/digit from 0 to 9 to it's bit representation on the display.
/// This is not the char (ASCII) representation. It's a number/integer.
pub const fn encode_digit(digit: u8) -> u8 {
let digit = digit % 10;
if digit == 0 {
NumCharBits::Zero as u8
} else if digit == 1 {
NumCharBits::One as u8
} else if digit == 2 {
NumCharBits::Two as u8
} else if digit == 3 {
NumCharBits::Three as u8
} else if digit == 4 {
NumCharBits::Four as u8
} else if digit == 5 {
NumCharBits::Five as u8
} else if digit == 6 {
NumCharBits::Six as u8
} else if digit == 7 {
NumCharBits::Seven as u8
} else if digit == 8 {
NumCharBits::Eight as u8
}
// else if digit == 9 { NumCharBits::Nine as u8 }
else {
NumCharBits::Nine as u8
}
}
/// Encodes a char for the 7-segment display. Unknown chars will be a zero byte (space).
/// Uses `mappings::UpCharBits` and `mappings::LoCharBits` for the chars. Since there is
/// no representation for every char in each case (lower, upper) there will be an replacement
/// for lowercase charts by their uppercase counterpart and vice versa.
#[allow(clippy::cognitive_complexity)]
#[allow(clippy::if_same_then_else)]
#[rustfmt::skip]
pub const fn encode_char(c: char) -> u8 {
// nums
if c == '0' { NumCharBits::Zero as u8 }
else if c == '1' { NumCharBits::One as u8 }
else if c == '2' { NumCharBits::Two as u8 }
else if c == '3' { NumCharBits::Three as u8 }
else if c == '4' { NumCharBits::Four as u8 }
else if c == '5' { NumCharBits::Five as u8 }
else if c == '6' { NumCharBits::Six as u8 }
else if c == '7' { NumCharBits::Seven as u8 }
else if c == '8' { NumCharBits::Eight as u8 }
else if c == '9' { NumCharBits::Nine as u8 }
// latin chars
// we map as accurate as possible,
// e.g.: a => lowercase a, A => uppercase A
//
// but in cases where we only have on mapping available
// like: b => lowercase b, B => undefined
// we map B => lowercase b
else if c == 'A' { UpCharBits::UpA as u8 }
else if c == 'a' { LoCharBits::LoA as u8 }
else if c == 'B' { LoCharBits::LoB as u8 }
else if c == 'b' { LoCharBits::LoB as u8 }
else if c == 'C' { UpCharBits::UpC as u8 }
else if c == 'c' { UpCharBits::UpC as u8 }
else if c == 'D' { LoCharBits::LoD as u8 }
else if c == 'd' { LoCharBits::LoD as u8 }
else if c == 'E' { UpCharBits::UpE as u8 }
else if c == 'e' { UpCharBits::UpE as u8 }
else if c == 'F' { UpCharBits::UpF as u8 }
else if c == 'f' { UpCharBits::UpF as u8 }
else if c == 'G' { UpCharBits::UpG as u8 }
else if c == 'g' { UpCharBits::UpG as u8 }
else if c == 'H' { UpCharBits::UpH as u8 }
else if c == 'h' { LoCharBits::LoH as u8 }
else if c == 'I' { UpCharBits::UpI as u8 }
else if c == 'i' { UpCharBits::UpI as u8 }
else if c == 'J' { UpCharBits::UpJ as u8 }
else if c == 'j' { UpCharBits::UpJ as u8 }
else if c == 'L' { UpCharBits::UpL as u8 }
else if c == 'l' { UpCharBits::UpL as u8 }
else if c == 'N' { LoCharBits::LoN as u8 }
else if c == 'n' { LoCharBits::LoN as u8 }
else if c == 'O' { UpCharBits::UpO as u8 }
else if c == 'o' { LoCharBits::LoO as u8 }
else if c == 'P' { UpCharBits::UpP as u8 }
else if c == 'p' { UpCharBits::UpP as u8 }
else if c == 'Q' { LoCharBits::LoQ as u8 }
else if c == 'q' { LoCharBits::LoQ as u8 }
else if c == 'R' { LoCharBits::LoR as u8 }
else if c == 'r' { LoCharBits::LoR as u8 }
else if c == 'S' { UpCharBits::UpS as u8 }
else if c == 's' { UpCharBits::UpS as u8 }
else if c == 'T' { LoCharBits::LoT as u8 }
else if c == 't' { LoCharBits::LoT as u8 }
else if c == 'U' { UpCharBits::UpU as u8 }
else if c == 'u' { LoCharBits::LoU as u8 }
else if c == 'Y' { LoCharBits::LoY as u8 }
else if c == 'y' { LoCharBits::LoY as u8 }
// special chars
else if c == ' ' { SpecialCharBits::Space as u8 }
else if c == '?' { SpecialCharBits::QuestionMark as u8 }
else if c == '-' { SpecialCharBits::Minus as u8 }
else if c == '_' { SpecialCharBits::Underscore as u8 }
else if c == '=' { SpecialCharBits::Equals as u8 }
else if c == '.' { SpecialCharBits::Dot as u8 }
else { SpecialCharBits::Space as u8 }
}
/// Encodes a string for the 7-segment display. This uses
/// `encode_char` for each character.
pub fn encode_string(str: &str) -> Vec<u8> {
str.chars().into_iter().map(Self::encode_char).collect()
}
/// This tells the TM1637 that data input starts.
/// This information stands in the official data sheet.
#[inline]
fn start(&self) {
(self.pin_dio_write_fn)(GpioPinValue::HIGH);
(self.pin_clock_write_fn)(GpioPinValue::HIGH);
self.bit_delay();
(self.pin_dio_write_fn)(GpioPinValue::LOW);
self.bit_delay();
// transition from high to low on DIO while CLK is high
// means: data starts at next clock
}
/// This tells the TM1637 that data input stops.
/// This information stands in the official data sheet.
#[inline]
fn stop(&self) {
(self.pin_dio_write_fn)(GpioPinValue::LOW);
(self.pin_clock_write_fn)(GpioPinValue::HIGH);
self.bit_delay();
(self.pin_dio_write_fn)(GpioPinValue::HIGH);
self.bit_delay();
}
/// Receives one acknowledgment after a byte was sent.
fn recv_ack(&self) {
(self.pin_clock_write_fn)(GpioPinValue::LOW);
(self.pin_dio_write_fn)(GpioPinValue::LOW);
self.bit_delay();
(self.pin_clock_write_fn)(GpioPinValue::HIGH);
let ack: GpioPinValue = (self.pin_dio_read_fn)();
// wait a few cycles for ACK to be more fail safe
for _ in 0..10 {
if ack as u8 == 0 {
break;
} else {
// ACK should be one clock with zero on data lane
// not possible with no_std; TODO provide debug function
// eprintln!("ack is not 0! Probably not a problem, tho.")
}
}
(self.pin_clock_write_fn)(GpioPinValue::LOW);
(self.pin_dio_write_fn)(GpioPinValue::LOW);
self.bit_delay();
}
/// Let the current thread sleep for the configured amount of µs.
/// This is necessary so that changed values on the pins (High, Low)
/// are applied. The best value here depends on your platform.
/// 100µs on Raspberry Pi with GPIO-Pins seems perfectly fine.
#[inline]
fn bit_delay(&self) {
(self.bit_delay_fn)()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_encode_number() {
let f = TM1637Adapter::encode_digit;
assert_eq!([f(1), f(2), f(3), f(4)], TM1637Adapter::encode_number(1234));
assert_eq!([f(9), f(9), f(9), f(9)], TM1637Adapter::encode_number(9999));
assert_eq!(
[f(0), f(0), f(0), f(0)],
TM1637Adapter::encode_number(10000)
);
assert_eq!([f(7), f(6), f(5), f(4)], TM1637Adapter::encode_number(7654));
}
}