From 08991060dacd0060126e621b3ac8ea44ca011a17 Mon Sep 17 00:00:00 2001 From: destroyedlolo Date: Sat, 24 Mar 2018 13:58:27 +0100 Subject: [PATCH] Add some comments about race condition --- examples/DS18B20_DHT22/DS18B20_DHT22.ino | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/examples/DS18B20_DHT22/DS18B20_DHT22.ino b/examples/DS18B20_DHT22/DS18B20_DHT22.ino index cb4f752..70b5ce5 100644 --- a/examples/DS18B20_DHT22/DS18B20_DHT22.ino +++ b/examples/DS18B20_DHT22/DS18B20_DHT22.ino @@ -55,6 +55,7 @@ void owRcv( OneWireSlave::ReceiveEvent evt, byte cmd ){ case OW_Cmd::START_CONVERSION: state = DeviceState::CONVERTING; OWSlave.beginWriteBit(0, true); // send zeros as long as the conversion is not finished + // consequently, we don't have to take care of race condition as no other command can arrive break; case OW_Cmd::READ_SCRATCHPAD: state = DeviceState::WAIT4RESET; @@ -72,6 +73,9 @@ void owRcv( OneWireSlave::ReceiveEvent evt, byte cmd ){ void setTemperature( float temp ){ // Write given temperature to the scratchpad int16_t raw = (int16_t)(temp * 16.0f + 0.5f); + // We don't care about race condition as well as only one command + // can be processed at a time otherwise we are failing in error/collision + // condition. scratchpad[0] = (byte)raw; scratchpad[1] = (byte)(raw >> 8); scratchpad[8] = OWSlave.crc8((const byte*)scratchpad, 8);