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i2c: half_period -> unit_delay

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Sebastien Bourdeauducq 2021-06-25 16:26:53 +08:00
parent 4159aab6c8
commit b0ec74d764
1 changed files with 22 additions and 22 deletions
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44
libboard_zynq/src/i2c/mod.rs
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@ -76,7 +76,7 @@ impl I2c {
nb::block!(self.count_down.wait()).unwrap(); nb::block!(self.count_down.wait()).unwrap();
} }
fn half_period(&mut self) { self.delay_us(100) } fn unit_delay(&mut self) { self.delay_us(100) }
fn sda_i(&mut self) -> bool { fn sda_i(&mut self) -> bool {
self.regs.gpio_input.read().sda() self.regs.gpio_input.read().sda()
@ -117,15 +117,15 @@ impl I2c {
self.sda_o(false); self.sda_o(false);
// Check the I2C bus is ready // Check the I2C bus is ready
self.half_period(); self.unit_delay();
self.half_period(); self.unit_delay();
if !self.sda_i() { if !self.sda_i() {
// Try toggling SCL a few times // Try toggling SCL a few times
for _bit in 0..8 { for _bit in 0..8 {
self.scl_oe(true); self.scl_oe(true);
self.half_period(); self.unit_delay();
self.scl_oe(false); self.scl_oe(false);
self.half_period(); self.unit_delay();
} }
} }
@ -148,9 +148,9 @@ impl I2c {
return Err("SDA arbitration lost"); return Err("SDA arbitration lost");
} }
self.sda_oe(true); self.sda_oe(true);
self.half_period(); self.unit_delay();
self.scl_oe(true); self.scl_oe(true);
self.half_period(); self.unit_delay();
// postcondition: SCL and SDA low // postcondition: SCL and SDA low
Ok(()) Ok(())
} }
@ -158,9 +158,9 @@ impl I2c {
pub fn restart(&mut self) -> Result<(), &'static str> { pub fn restart(&mut self) -> Result<(), &'static str> {
// precondition SCL and SDA low // precondition SCL and SDA low
self.sda_oe(false); self.sda_oe(false);
self.half_period(); self.unit_delay();
self.scl_oe(false); self.scl_oe(false);
self.half_period(); self.unit_delay();
self.start()?; self.start()?;
// postcondition: SCL and SDA low // postcondition: SCL and SDA low
Ok(()) Ok(())
@ -168,11 +168,11 @@ impl I2c {
pub fn stop(&mut self) -> Result<(), &'static str> { pub fn stop(&mut self) -> Result<(), &'static str> {
// precondition: SCL and SDA low // precondition: SCL and SDA low
self.half_period(); self.unit_delay();
self.scl_oe(false); self.scl_oe(false);
self.half_period(); self.unit_delay();
self.sda_oe(false); self.sda_oe(false);
self.half_period(); self.unit_delay();
if !self.sda_i() { if !self.sda_i() {
return Err("SDA arbitration lost"); return Err("SDA arbitration lost");
} }
@ -185,20 +185,20 @@ impl I2c {
// MSB first // MSB first
for bit in (0..8).rev() { for bit in (0..8).rev() {
self.sda_oe(data & (1 << bit) == 0); self.sda_oe(data & (1 << bit) == 0);
self.half_period(); self.unit_delay();
self.scl_oe(false); self.scl_oe(false);
self.half_period(); self.unit_delay();
self.scl_oe(true); self.scl_oe(true);
self.half_period(); self.unit_delay();
} }
self.sda_oe(false); self.sda_oe(false);
self.half_period(); self.unit_delay();
self.scl_oe(false); self.scl_oe(false);
self.half_period(); self.unit_delay();
// Read ack/nack // Read ack/nack
let ack = !self.sda_i(); let ack = !self.sda_i();
self.scl_oe(true); self.scl_oe(true);
self.half_period(); self.unit_delay();
self.sda_oe(true); self.sda_oe(true);
// postcondition: SCL and SDA low // postcondition: SCL and SDA low
@ -213,17 +213,17 @@ impl I2c {
// MSB first // MSB first
for bit in (0..8).rev() { for bit in (0..8).rev() {
self.half_period(); self.unit_delay();
self.scl_oe(false); self.scl_oe(false);
self.half_period(); self.unit_delay();
if self.sda_i() { data |= 1 << bit } if self.sda_i() { data |= 1 << bit }
self.scl_oe(true); self.scl_oe(true);
} }
// Send ack/nack // Send ack/nack
self.sda_oe(ack); self.sda_oe(ack);
self.half_period(); self.unit_delay();
self.scl_oe(false); self.scl_oe(false);
self.half_period(); self.unit_delay();
self.scl_oe(true); self.scl_oe(true);
self.sda_oe(true); self.sda_oe(true);
// postcondition: SCL and SDA low // postcondition: SCL and SDA low