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OneWire.c
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/* ************************************************************************
*
* OneWire communication and tools
*
* (c) 2018-2021 by Markus Reschke
*
* ************************************************************************ */
/*
* hints:
* - DQ (data line) requires a 4.7kOhms pull-up resistor to Vcc
* - pin assignment for probes (ONEWIRE_PROBES)
* probe #1 Gnd
* probe #2 DQ (requires 4.7kOhms pull-up resistor to Vcc)
* probe #3 Vcc (via Rl to limit current)
* - port and pins for dedicated MCU pin (ONEWIRE_IO_PIN)
* ONEWIRE_PORT port data register
* ONEWIRE_DDR port data direction register
* ONEWIRE_PIN port input pins register
* ONEWIRE_DQ pin for DQ
* - standard-speed (accurate 1µs delay)
* - external power for clients (no parasite power)
*/
/* local includes */
#include "config.h" /* global configuration */
#if defined (ONEWIRE_IO_PIN) || defined (ONEWIRE_PROBES)
/*
* local constants
*/
/* source management */
#define ONEWIRE_C
/* operation modes */
#define MODE_MANUAL 0 /* manual mode */
#define MODE_AUTO 1 /* automatic mode */
/*
* include header files
*/
/* local includes */
#include "common.h" /* common header file */
#include "variables.h" /* global variables */
#include "functions.h" /* external functions */
#include "OneWire.h" /* OneWire specifics */
/*
* local variables
*/
/* CRC */
uint8_t CRC8; /* current CRC-8 */
#if defined (ONEWIRE_READ_ROM) || defined (SW_ONEWIRE_SCAN)
/* ROM code */
uint8_t ROM_Code[8]; /* ROM code */
uint8_t LastCon; /* bit position of last code conflict */
#endif
/* ************************************************************************
* low level functions
* ************************************************************************ */
#ifdef ONEWIRE_IO_PIN
/*
* set up OneWire bus
* - DQ line
*/
void OneWire_Setup(void)
{
/*
* DQ is driven as open-drain output
* and pulled up by external 4.7kOhm resistor
*/
/* set DQ to input mode */
ONEWIRE_DDR &= ~(1 << ONEWIRE_DQ); /* clear bit */
/* preset DQ to low for output mode */
ONEWIRE_PORT &= ~(1 << ONEWIRE_DQ); /* clear bit */
}
#endif
#ifdef ONEWIRE_PROBES
/*
* set up probes for OneWire bus
* - probe-1: Gnd
* - probe-2: DQ (pull-up resistor required)
* - probe-3: Vcc (current limited by Rl)
*
* requires:
* - String: string stored in EEPROM for first display line
*
* returns:
* - 1 on success
* - 0 on any problem
*/
uint8_t OneWire_Probes(const unsigned char *String)
{
uint8_t Flag = 0; /* return value */
uint8_t Run = 1; /* loop control */
/* inform user in line #1 */
ShortCircuit(0); /* make sure probes are not shorted */
LCD_Clear();
#ifdef UI_COLORED_TITLES
Display_ColoredEEString(String, COLOR_TITLE); /* display String */
#else
Display_EEString(String); /* display String */
#endif
/* display module pinout (1: Gnd / 2: Data / 3: Vcc) */
Display_NextLine();
Show_SimplePinout('-', 'd', '+');
/* set probes: probe-1 -- Gnd / probe-3 -- Rl -- Vcc / probe-2 (HiZ) -- Rh -- Gnd */
/* pull up probe-3 via Rl, pull down probe-2 via Rh */
R_DDR = (1 << R_RL_3) | (1 << R_RH_2); /* enable resistors */
R_PORT = (1 << R_RL_3); /* pull up probe-3, pull down probe-2 */
ADC_PORT = 0; /* pull down directly: */
ADC_DDR = (1 << TP1); /* probe-1 */
wait20ms(); /* time to settle */
/* wait for external pull-up resistor or key press */
while (Run)
{
if (ADC_PIN & (1 << TP2)) /* check for high level of probe-2 */
{
Flag = 1; /* signal "bus ok" */
Run = 0; /* end loop */
}
else /* check test key */
{
/* wait 100ms for key press */
Flag = TestKey(100, CHECK_BAT);
if (Flag) /* key pressed */
{
Flag = 0; /* signal "skipped" */
Run = 0; /* end loop */
}
}
}
/* remove pull-down via Rh for probe-2 */
R_DDR = (1 << R_RL_3); /* disable Rh for probe-2 */
return Flag;
}
#endif
/*
* reset bus and check for presence pulse from client(s)
*
* returns:
* - 0: no presence pulse from client
* - 1: presence pulse from client
*/
uint8_t OneWire_ResetBus(void)
{
uint8_t Flag = 0; /* return value */
/*
* pull down DQ for >=480µs and release it again
*/
#ifdef ONEWIRE_IO_PIN
/* change DQ to output mode (port pin is low) */
ONEWIRE_DDR |= (1 << ONEWIRE_DQ); /* set bit */
#endif
#ifdef ONEWIRE_PROBES
/* change probe-2 (DQ) to output mode (port pin is low) */
ADC_DDR |= (1 << TP2); /* set bit */
#endif
wait500us(); /* delay of 500µs */
#ifdef ONEWIRE_IO_PIN
/* change DQ back to input mode */
ONEWIRE_DDR &= ~(1 << ONEWIRE_DQ); /* clear bit */
#endif
#ifdef ONEWIRE_PROBES
/* change probe-2 (DQ) back to input mode */
ADC_DDR &= ~(1 << TP2); /* clear bit */
#endif
/*
* check for presence pulse from client(s)
* - time slot >=480µs
* - client responds after 15-60µs with a low pulse of 60-240µs
* - we check DQ after 70µs
*/
wait50us(); /* read delay of 70µs */
wait20us();
#ifdef ONEWIRE_IO_PIN
/* read DQ */
if (! (ONEWIRE_PIN & (1 << ONEWIRE_DQ))) /* low */
{
Flag = 1; /* signal ok */
}
#endif
#ifdef ONEWIRE_PROBES
/* read DQ (probe-2) */
if (! (ADC_PIN & (1 << TP2))) /* low */
{
Flag = 1; /* signal ok */
}
#endif
/* end the time slot */
wait400us(); /* delay of 430µs (500µs - 70µs) */
wait30us();
return Flag;
}
/*
* send bit
*
* requires:
* - Bit: 0/1
*/
void OneWire_SendBit(uint8_t Bit)
{
/*
* - write time slot: 60-120µs
* - recovery time after write: >=1µs
* - write "1":
* - 1-15µs low pulse
* - release DQ and wait until end of time slot
* - write "0":
* - 60-120µs low pulse (complete time slot)
* - release DQ
*/
/*
* pull down DQ
*/
#ifdef ONEWIRE_IO_PIN
/* change DQ to output mode (port pin is low) */
ONEWIRE_DDR |= (1 << ONEWIRE_DQ); /* set bit */
#endif
#ifdef ONEWIRE_PROBES
/* change probe-2 (DQ) to output mode (port pin is low) */
ADC_DDR |= (1 << TP2); /* set bit */
#endif
if (Bit) /* 1 */
{
/*
* pull down DQ for 5µs and release it again
*/
wait5us(); /* pulse delay of 5µs */
#ifdef ONEWIRE_IO_PIN
/* change DQ back to input mode */
ONEWIRE_DDR &= ~(1 << ONEWIRE_DQ); /* clear bit */
#endif
#ifdef ONEWIRE_PROBES
/* change probe-2 (DQ) back to input mode */
ADC_DDR &= ~(1 << TP2); /* clear bit */
#endif
/* end the time slot + recovery time */
wait50us(); /* delay of 65µs */
wait5us();
wait10us();
}
else /* 0 */
{
/*
* pull down DQ for 60µs and release it again
*/
wait50us(); /* pulse delay of 60µs */
wait10us();
#ifdef ONEWIRE_IO_PIN
/* change DQ back to input mode */
ONEWIRE_DDR &= ~(1 << ONEWIRE_DQ); /* clear bit */
#endif
#ifdef ONEWIRE_PROBES
/* change probe-2 (DQ) back to input mode */
ADC_DDR &= ~(1 << TP2); /* clear bit */
#endif
/* recovery time */
wait10us(); /* delay of 10µs */
}
}
/*
* read bit
*
* returns:
* - Bit: 0/1
*/
uint8_t OneWire_ReadBit(void)
{
uint8_t Bit = 0; /* return value */
/*
* - read time slot: 60-120µs
* - recovery time after read: >=1µs
* - master starts read process by a low pulse >=1µs
* - client's response is valid for 15µs after falling edge of
* the master's low pulse
* - we read DQ after 13µs
*/
/*
* pull down DQ for 5µs and release it again
*/
#ifdef ONEWIRE_IO_PIN
/* change DQ to output mode (port pin is low) */
ONEWIRE_DDR |= (1 << ONEWIRE_DQ); /* set bit */
#endif
#ifdef ONEWIRE_PROBES
/* change probe-2 (DQ) to output mode (port pin is low) */
ADC_DDR |= (1 << TP2); /* set bit */
#endif
wait5us(); /* pulse delay of 5µs */
#ifdef ONEWIRE_IO_PIN
/* change DQ back to input mode */
ONEWIRE_DDR &= ~(1 << ONEWIRE_DQ); /* clear bit */
#endif
#ifdef ONEWIRE_PROBES
/* change probe-2 (DQ) back to input mode */
ADC_DDR &= ~(1 << TP2); /* clear bit */
#endif
/*
* read client's response
* - data bit valid for 15µs starting with master's read pulse
* - high -> 1
* - low -> 0
*/
wait5us(); /* read delay of 8µs */
wait3us();
#ifdef ONEWIRE_IO_PIN
/* read DQ */
if (ONEWIRE_PIN & (1 << ONEWIRE_DQ)) /* high */
{
Bit = 1; /* 1 */
}
#endif
#ifdef ONEWIRE_PROBES
/* read DQ (probe-2) */
if (ADC_PIN & (1 << TP2)) /* high */
{
Bit = 1; /* 1 */
}
#endif
/* end the time slot + recovery time */
wait50us(); /* delay of 57µs */
wait5us();
wait2us();
return Bit;
}
/*
* send byte
* - sending bit order: LSB
*
* requires:
* - Byte: data byte
*/
void OneWire_SendByte(uint8_t Byte)
{
uint8_t n = 0; /* counter */
while (n < 8) /* 8 bits */
{
OneWire_SendBit(Byte & 0x01); /* send LSB */
Byte >>= 1; /* shift to right */
n++; /* next bit */
}
}
/*
* read byte
* - reading bit order: LSB
*
* returns:
* - Byte: data byte
*/
uint8_t OneWire_ReadByte(void)
{
uint8_t Byte = 0; /* return value */
uint8_t n = 0; /* counter */
while (n < 8) /* 8 bits */
{
Byte >>= 1; /* shift to right */
if (OneWire_ReadBit()) /* read "1" */
{
Byte |= 0b10000000; /* set bit */
}
n++; /* next bit */
}
return Byte;
}
/* ************************************************************************
* high level functions
* ************************************************************************ */
#if 0
/*
* address client
* - includes reset of the bus
* - transaction steps: initialization and ROM command
*
* requires:
* - ROM_Code: pointer to ROM code stored in an array of 8 bytes
*
* returns:
* - 1
* - 0
*/
uint8_t OneWire_AddressClient(uint8_t *ROM_Code)
{
uint8_t Flag = 0; /* return value */
uint8_t n = 0; /* counter */
/* transaction: initialization */
/* reset bus and check for presence pulse */
Flag = OneWire_ResetBus();
if (Flag) /* detected client(s) */
{
/* transaction: ROM command */
if (ROM_Code) /* valid pointer */
{
/* address specific client on the bus */
OneWire_SendByte(CMD_MATCH_ROM); /* select client with ROM code */
/* send client's ROM code */
while (n < 8) /* 8 bytes */
{
OneWire_SendByte(*ROM_Code); /* send one byte of ROM code */
ROM_Code++; /* next byte */
n++; /* next byte */
}
}
else /* NULL pointer */
{
/* assumes a single client on the bus */
OneWire_SendByte(CMD_SKIP_ROM); /* select all clients */
}
}
return Flag;
}
#endif
/*
* calculate CRC-8
* - CRC = X^8 + X^5 + X^4 + 1
* - start value: 0x00
* - uses variable CRC8 to track current CRC
*
* requires:
* - Byte: new input byte
*/
void OneWire_CRC8(uint8_t Byte)
{
uint8_t n = 0; /* counter */
uint8_t Bit; /* LSB */
while (n < 8) /* 8 bits */
{
/* XOR current LSB of input with CRC8's current X^8 */
Bit = CRC8 ^ Byte; /* XOR */
Bit &= 0b00000001; /* filter LSB */
/* shift CRC right */
CRC8 >>= 1; /* for next bit */
if (Bit) /* XORed LSB is 1 */
{
/*
* XOR CRC's X^5 and X^4 with 1
* - XOR with 0b00011000
* - since CRC is already shifted right: XOR with 0b00001100
* - since we have to feed the XORed LSB back into the CRC
* and the MSB is 0 after shifting: XOR with 0b10001100
*/
CRC8 ^= 0b10001100; /* XOR */
}
/* when 0:
* - XOR would keep the original bits
* - MSB will be 0 after a right shift anyway
*/
/* shift input right */
Byte >>= 1; /* for next input bit */
n++; /* next bit */
}
}
/* ************************************************************************
* Search ROM
* ************************************************************************ */
#ifdef SW_ONEWIRE_SCAN
/*
* search for next device (ROM code)
*
* returns:
* - 2 found last device
* - 1 found next device
* - 0 on any problem
*/
uint8_t OneWire_Next_ROM_Code(void)
{
uint8_t Flag; /* return value */
uint8_t BitPos = 1; /* bit position of ROM code */
uint8_t NewCon = 0; /* bit position of code conflict */
uint8_t Bit1; /* bit */
uint8_t Bit2; /* bit complement */
uint8_t NewBit; /* bit to send */
uint8_t CodeByte = 0; /* byte counter for ROM code */
uint8_t CodeBit = 1; /* bitmask for ROM code */
uint8_t Temp; /* temporary value */
wdt_reset(); /* reset watchdog */
/* transaction: initialization */
/* reset bus and check for presence pulse */
Flag = OneWire_ResetBus();
if (Flag) /* detected client */
{
/* transaction: ROM command */
OneWire_SendByte(CMD_SEARCH_ROM); /* search ROM */
/*
* processing loop
*/
while (BitPos < 65) /* 64 bits */
{
NewBit = 2; /* default: invalid */
/* read bit and its complement */
Bit1 = OneWire_ReadBit(); /* read bit */
Bit2 = OneWire_ReadBit(); /* read complement */
/* process bits */
if (Bit1 != Bit2) /* valid bit (01 or 10) */
{
NewBit = Bit1; /* copy bit */
}
else if (Bit1 & Bit2) /* no response (11) */
{
BitPos = 64; /* end loop */
Flag = 0; /* signal bus error */
}
else /* code conflict (00) */
{
if (LastCon < BitPos) /* code conflict further up */
{
/* start branch with 0 */
NewBit = 0; /* set bit to 0 */
NewCon = BitPos; /* update bit position */
}
else if (LastCon == BitPos) /* hit pos of last code conflict */
{
/* change branch to 1 */
NewBit = 1; /* set bit to 1 */
}
else /* LastCon > BitPos */ /* code conflict further down */
{
/* get bit from ROM code */
Temp = ROM_Code[CodeByte] & CodeBit;
if (Temp == 0) /* bit is 0 */
{
NewCon = BitPos; /* update bit position */
/* this is going to be 1 in the next search run */
}
NewBit = Temp; /* use bit from ROM code */
}
}
/* process bit to send */
if (NewBit < 2) /* valid bit */
{
/* update ROM code */
if (NewBit == 0) /* bit is 0 */
{
ROM_Code[CodeByte] &= ~CodeBit; /* clear bit in ROM code */
}
else /* bit is 1 */
{
ROM_Code[CodeByte] |= CodeBit; /* set bit in ROM code */
}
/* send bit to select branch */
OneWire_SendBit(NewBit);
}
/* loop management */
if (CodeBit & 0b10000000) /* bitmask overflow */
{
CodeBit = 0b00000001; /* reset bitmask to first bit */
CodeByte++; /* next byte */
}
else /* no overflow */
{
CodeBit <<= 1; /* shift left by one */
}
BitPos++; /* next bit */
}
/* manage branching for next run */
LastCon = NewCon; /* update bit position of code conflict */
if (LastCon == 0) /* no devices left */
{
if (Flag) /* don't overwrite error */
{
Flag = 2; /* signal last device */
}
}
/* special case: all zero (pull-up resistor suddenly missing) */
if (ROM_Code[0] == 0) /* family code 00 */
{
Flag = 0; /* signal bus error */
}
}
return Flag;
}
/*
* read ROM codes of connected devices
*
* returns:
* - 1 on success
* - 0 on any problem
*/
uint8_t OneWire_Scan_Tool(void)
{
uint8_t Flag; /* return value */
uint8_t Run; /* loop control */
uint8_t Test; /* key / feedback */
uint8_t n; /* counter */
/* local constants */
#define RUN_FLAG 0b00000001 /* run */
#define RESET_FLAG 0b00000010 /* reset values */
#define OUTPUT_FLAG 0b00000100 /* output ROM code */
#define DONE_FLAG 0b00001000 /* last device */
#ifdef ONEWIRE_IO_PIN
Flag = 1; /* set default */
#endif
#ifdef ONEWIRE_PROBES
/* inform user about pinout and check for external pull-up resistor */
Flag = OneWire_Probes(OneWire_Scan_str);
if (Flag == 0) /* bus error */
{
return Flag; /* exit tool and signal error */
}
#endif
LCD_ClearLine2(); /* clear line #2 */
Display_EEString(Start_str); /* display: Start */
UI.LineMode = LINE_STD | LINE_KEEP; /* next-line mode: keep first line */
/*
* processing loop
*/
Run = RUN_FLAG | RESET_FLAG;
while (Run)
{
n = UI.CharPos_Y; /* get current line number */
/* user input */
/* wait for user input */
Test = TestKey(0, CURSOR_BLINK | CHECK_KEY_TWICE | CHECK_BAT);
if (Test == KEY_TWICE) /* two short key presses */
{
break; /* end loop */
}
/* reset values */
if (Run & RESET_FLAG) /* reset requested */
{
/* clear ROM code */
for (n = 0; n < 8; n++) /* 8 bytes */
{
ROM_Code[n] = 0;
}
LastCon = 0; /* reset bit position of last code conflict */
Run &= ~RESET_FLAG; /* clear flag */
}
else /* consecutive run */
{
LCD_CharPos(1, n); /* move to beginning of former line */
}
/* manage screen */
Display_NextLine(); /* move to next line */
/* search for next device */
if (Run) /* ok to proceed */
{
Test = OneWire_Next_ROM_Code(); /* get next device */
if (Test >= 1) /* got ROM code */
{
/* check CRC */
CRC8 = 0x00; /* reset CRC to start value */
n = 0;
while (n < 7) /* 7 data bytes */
{
OneWire_CRC8(ROM_Code[n]); /* process byte */
n++; /* next byte */
}
if (ROM_Code[7] == CRC8) /* CRC matches */
{
Run |= OUTPUT_FLAG; /* output ROM code */
}
else /* mismatch */
{
Display_EEString_Space(CRC_str); /* display: CRC */
Display_EEString(Error_str); /* display: error */
}
if (Test == 2) /* no devices left */
{
Run |= DONE_FLAG; /* last ROM code */
}
}
else /* error */
{
Display_EEString_Space(Bus_str); /* display: Bus */
Display_EEString(Error_str); /* display: error */
Run |= RESET_FLAG; /* reset values for next scan */
}
}
/* display ROM code */
if (Run & OUTPUT_FLAG) /* output requested */
{
/* display family code */
Display_HexByte(ROM_Code[0]); /* display family */
Display_Space(); /* display space */
/* display serial number (MSB left) */
for (n = 6; n > 0; n--) /* 6 bytes */
{
Display_HexByte(ROM_Code[n]); /* display S/N */
}
Run &= ~OUTPUT_FLAG; /* clear flag */
}
/* indicate end of scan */
if (Run & DONE_FLAG) /* no devices left */
{
Display_NL_EEString(Done_str); /* display: done */
Run |= RESET_FLAG; /* reset values for next scan */
Run &= ~DONE_FLAG; /* clear flag */
}
}
return Flag;
/* clean up */
#undef RUN_FLAG
#undef RESET_FLAG
#undef OUTPUT_FLAG
#undef DONE_FLAG
}
#endif
/* ************************************************************************
* Read ROM
* ************************************************************************ */
#ifdef ONEWIRE_READ_ROM
/*
* read ROM code of connected device
* - single client on the bus
* - also display ROM code
*/
void OneWire_Read_ROM_Code(void)
{
uint8_t Flag = 0; /* control flag */
uint8_t n; /* counter */
wdt_reset(); /* reset watchdog */
/* transaction: initialization */
/* reset bus and check for presence pulse */
Flag = OneWire_ResetBus();
if (Flag) /* detected client */
{
/* transaction: ROM command */
OneWire_SendByte(CMD_READ_ROM); /* read ROM */
/* read 8 bytes */
n = 0;
while (n < 8) /* 8 bytes */
{
ROM_Code[n] = OneWire_ReadByte(); /* read byte */
n++; /* next byte */
}
/* check CRC */
CRC8 = 0x00; /* reset CRC to start value */
n = 0;
while (n < 7) /* 7 data bytes */
{
OneWire_CRC8(ROM_Code[n]); /* process byte */
n++; /* next byte */
}
if (ROM_Code[7] == CRC8) /* CRC matches */
{
/* output ROM code */
/* display family code */
Display_HexByte(ROM_Code[0]); /* display family */
Display_Space(); /* display space */
/* display serial number (MSB left) */
for (n = 6; n > 0; n--) /* 6 bytes */
{
Display_HexByte(ROM_Code[n]); /* display S/N */
}
}
else /* mismatch */
{
Display_Minus(); /* display n/a */
}
}
}
#endif
/* ************************************************************************
* DS18B20
* ************************************************************************ */
#ifdef SW_DS18B20
/*
* DS18B20: read temperature
* - single client on the bus
*
* requires:
* - Value: pointer to temperature in °C
* - Scale: pointer to scale factor (*10^x)
*
* returns:
* - 1 on success
* - 0 on any problem
*/
uint8_t DS18B20_ReadTemperature(int32_t *Value, int8_t *Scale)
{
uint8_t Flag = 0; /* return value / control flag */
uint8_t Run = 0; /* loop control */
uint8_t n; /* counter */
uint8_t ScratchPad[9]; /* scratchpad */
uint8_t Sign; /* sign flag */
int16_t Temp; /* temperature */
wdt_reset(); /* reset watchdog */
/* transaction: initialization */
/* reset bus and check for presence pulse */
Flag = OneWire_ResetBus();
if (Flag) /* detected client */
{
/* transaction: ROM command */
OneWire_SendByte(CMD_SKIP_ROM); /* select all clients */
/* transaction: function command */
/* start conversion */
OneWire_SendByte(CMD_DS18B20_CONVERT_T);
/*
* maximum conversion time
* - 9 bits 93.75ms (t_conv/8)
* - 10 bits 187.5ms (t_conv/4)
* - 11 bits 375ms (t_conv/2)
* - 12 bits 750ms (t_conv)
*/