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use crate::prelude::*;
use rust_hdl_core::prelude::*;
#[derive(Copy, Clone, PartialEq, Debug, LogicState)]
enum State {
Idle,
Start,
Reading,
Waiting,
Flag,
Ack,
AckHold,
WaitEndTransaction,
CheckStop,
Writing,
WaitSCLHigh,
WaitSCLLow,
WaitSCLHighAck,
CollectAck,
}
#[derive(LogicBlock, Default)]
pub struct I2CTarget {
pub i2c: I2CBusDriver,
pub clock: Signal<In, Clock>,
pub from_bus: Signal<Out, Bits<8>>,
pub bus_write: Signal<Out, Bit>,
pub active: Signal<In, Bit>,
pub stop: Signal<Out, Bit>,
pub to_bus: Signal<In, Bits<8>>,
pub write_enable: Signal<In, Bit>,
pub ack: Signal<Out, Bit>,
pub nack: Signal<Out, Bit>,
pub write_ok: Signal<Out, Bit>,
state: DFF<State>,
scl_is_high: Signal<Local, Bit>,
sda_is_high: Signal<Local, Bit>,
sda_flop: DFF<Bit>,
clear_sda: Signal<Local, Bit>,
set_sda: Signal<Local, Bit>,
read_bit: DFF<Bit>,
count: DFF<Bits<4>>,
accum: DFF<Bits<8>>,
}
impl Logic for I2CTarget {
#[hdl_gen]
fn update(&mut self) {
dff_setup!(self, clock, state, sda_flop, read_bit, count, accum);
self.i2c.scl.drive_low.next = false;
self.i2c.sda.drive_low.next = self.sda_flop.q.val();
self.sda_is_high.next = self.i2c.sda.line_state.val();
self.scl_is_high.next = self.i2c.scl.line_state.val();
self.set_sda.next = false;
self.clear_sda.next = false;
self.from_bus.next = self.accum.q.val();
self.bus_write.next = false;
self.stop.next = false;
self.ack.next = false;
self.nack.next = false;
self.write_ok.next = false;
match self.state.q.val() {
State::Idle => {
self.set_sda.next = true;
self.count.d.next = 0.into();
if !self.sda_is_high.val() & self.scl_is_high.val() {
self.state.d.next = State::Start;
}
}
State::Start => {
if self.sda_is_high.val() {
self.state.d.next = State::Idle;
} else if !self.sda_is_high.val() & !self.scl_is_high.val() {
self.state.d.next = State::Reading;
}
}
State::Writing => {
if self.accum.q.val().get_bit(7) {
self.set_sda.next = true;
} else {
self.clear_sda.next = true;
}
self.count.d.next = self.count.q.val() + 1;
self.accum.d.next = self.accum.q.val() << 1;
self.state.d.next = State::WaitSCLHigh;
if self.count.q.val() == 8 {
self.state.d.next = State::WaitSCLHighAck;
}
}
State::WaitSCLHighAck => {
if self.scl_is_high.val() {
self.set_sda.next = true;
self.state.d.next = State::CollectAck;
}
}
State::CollectAck => {
if !self.scl_is_high.val() {
if self.sda_is_high.val() {
self.nack.next = true;
} else {
self.ack.next = true;
}
self.state.d.next = State::Reading;
}
}
State::WaitSCLHigh => {
if self.scl_is_high.val() {
self.state.d.next = State::WaitSCLLow;
}
}
State::WaitSCLLow => {
if !self.scl_is_high.val() {
self.state.d.next = State::Writing;
}
}
State::Reading => {
self.write_ok.next = true;
if self.write_enable.val() {
self.accum.d.next = self.to_bus.val();
self.count.d.next = 0.into();
self.state.d.next = State::Writing;
}
if self.scl_is_high.val() {
self.read_bit.d.next = self.sda_is_high.val();
self.state.d.next = State::Waiting;
}
}
State::Waiting => {
if !self.scl_is_high.val() {
self.accum.d.next =
(self.accum.q.val() << 1) | bit_cast::<8, 1>(self.read_bit.q.val().into());
self.count.d.next = self.count.q.val() + 1;
if self.count.q.val() == 7 {
self.state.d.next = State::Flag;
} else {
self.state.d.next = State::Reading;
}
}
if !self.read_bit.q.val() & self.sda_is_high.val() & self.scl_is_high.val() {
self.stop.next = true;
self.state.d.next = State::Idle;
}
if self.read_bit.q.val() & !self.sda_is_high.val() & self.scl_is_high.val() {
self.stop.next = true;
self.state.d.next = State::Idle;
}
}
State::Flag => {
self.bus_write.next = true;
self.accum.d.next = 0.into();
self.count.d.next = 0.into();
self.state.d.next = State::Ack;
}
State::Ack => {
self.clear_sda.next = self.active.val();
if !self.active.val() {
self.state.d.next = State::WaitEndTransaction;
}
if self.scl_is_high.val() {
self.state.d.next = State::AckHold;
}
}
State::AckHold => {
if !self.scl_is_high.val() {
self.set_sda.next = true;
self.state.d.next = State::Reading;
}
}
State::WaitEndTransaction => {
if self.scl_is_high.val() & !self.sda_is_high.val() {
self.state.d.next = State::CheckStop;
}
}
State::CheckStop => {
if self.scl_is_high.val() & self.sda_is_high.val() {
self.state.d.next = State::Idle;
self.stop.next = true;
}
}
_ => {
self.state.d.next = State::Idle;
}
}
if self.set_sda.val() {
self.sda_flop.d.next = false;
}
if self.clear_sda.val() {
self.sda_flop.d.next = true;
}
}
}