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i2c: fix comments

fix/i2c-race
Harry Ho 2021-07-13 15:14:53 +08:00
parent 91445620ee
commit 88bda0cb7a
1 changed files with 4 additions and 4 deletions
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8
libboard_zynq/src/i2c/mod.rs
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@ -190,7 +190,7 @@ impl I2c {
self.scl_oe(false); self.scl_oe(false);
self.half_period(); self.half_period();
self.scl_oe(true); self.scl_oe(true);
while self.scl_i() {} // ensure SCL is low before start() returns while self.scl_i() {} // ensure SCL is low before toggling SDA
} }
self.sda_oe(false); self.sda_oe(false);
self.half_period(); self.half_period();
@ -199,7 +199,7 @@ impl I2c {
// Read ack/nack // Read ack/nack
let ack = !self.sda_i(); let ack = !self.sda_i();
self.scl_oe(true); self.scl_oe(true);
while self.scl_i() {} // ensure SCL is low before start() returns while self.scl_i() {} // ensure SCL is low before toggling SDA
self.sda_oe(true); self.sda_oe(true);
// postcondition: SCL and SDA low // postcondition: SCL and SDA low
@ -219,7 +219,7 @@ impl I2c {
self.half_period(); self.half_period();
if self.sda_i() { data |= 1 << bit } if self.sda_i() { data |= 1 << bit }
self.scl_oe(true); self.scl_oe(true);
while self.scl_i() {} // ensure SCL is low before start() returns while self.scl_i() {} // ensure SCL is low so that slave can toggle SDA
} }
// Send ack/nack // Send ack/nack
self.sda_oe(ack); self.sda_oe(ack);
@ -227,7 +227,7 @@ impl I2c {
self.scl_oe(false); self.scl_oe(false);
self.half_period(); self.half_period();
self.scl_oe(true); self.scl_oe(true);
while self.scl_i() {} // ensure SCL is low before start() returns while self.scl_i() {} // ensure SCL is low before toggling SDA
self.sda_oe(true); self.sda_oe(true);
// postcondition: SCL and SDA low // postcondition: SCL and SDA low