Basic support for 1-Wire(R) communications. More...

#include <bsp430/periph/port.h>

Data Structures
struct	sBSP430onewireBus

struct	sBSP430onewireSerialNumber

Macros
#define	BSP430_ONEWIRE_xCel_TO_ddegF(xcel_) (320 + ((9 * (xcel_)) / 8))

#define	BSP430_ONEWIRE_xCel_TO_dK(xcel_) ((21852U + 5U * (xcel_)) / 8U)

Typedefs
typedef struct sBSP430onewireBus	sBSP430onewireBus

typedef struct sBSP430onewireSerialNumber	sBSP430onewireSerialNumber

Enumerations
enum	{ BSP430_ONEWIRE_CMD_READ_ROM = 0x33, BSP430_ONEWIRE_CMD_SKIP_ROM = 0xcc, BSP430_ONEWIRE_CMD_READ_POWER_SUPPLY = 0xb4, BSP430_ONEWIRE_CMD_RECALL_EE = 0xb8, BSP430_ONEWIRE_CMD_READ_SCRATCHPAD = 0xbe, BSP430_ONEWIRE_CMD_CONVERT_T = 0x44 }

Functions
int	iBSP430onewireReset_ni (const sBSP430onewireBus *bus)

void	vBSP430onewireShutdown_ni (const sBSP430onewireBus *bus)

void	vBSP430onewireWriteByte_ni (const sBSP430onewireBus *bus, int byte)

int	iBSP430onewireReadBit_ni (const sBSP430onewireBus *bus)

int	iBSP430onewireReadByte_ni (const sBSP430onewireBus *bus)

int	iBSP430onewireComputeCRC (const unsigned char *data, int len)

int	iBSP430onewireReadSerialNumber (const sBSP430onewireBus bus, sBSP430onewireSerialNumber snp)

int	iBSP430onewireReadPowerSupply (const sBSP430onewireBus *bus)

int	iBSP430onewireRequestTemperature_ni (const sBSP430onewireBus *bus)

static BSP430_CORE_INLINE int	iBSP430onewireTemperatureReady_ni (const sBSP430onewireBus *bus)

int	iBSP430onewireReadTemperature_ni (const sBSP430onewireBus bus, int temp_xCel)

Detailed Description

Basic support for 1-Wire(R) communications.

This currently supports enough to use DS18X one-wire temperature sensors with a dedicated bus and external power. Multiple devices on the bus, and parasite powered devices, have not been tested.

Homepage: http://github.com/pabigot/bsp430

Copyright: Copyright 2012-2014, Peter A. Bigot. Licensed under BSD-3-Clause

Macro Definition Documentation

#define BSP430_ONEWIRE_xCel_TO_ddegF ( xcel_ ) (320 + ((9 * (xcel_)) / 8))

Convert temperature from 1/16th Cel to tenths Fahrhenheit (d[degF])

For those of us who live in the US.

9 * t / 8 == (9/5) * 10 * (t / 16) without incidental overflow

Examples:: sensors/ds18b20/main.c.

#define BSP430_ONEWIRE_xCel_TO_dK ( xcel_ ) ((21852U + 5U * (xcel_)) / 8U)

Convert temperature from 1/16th Cel to tenths Kelvin (dK)

For those of us who obey the instruction of the Unified Code for Units of Measure

10 * (273.15 + x / 16) = (16*27315 + 100*x) / 160 = (437040 + 100 * x) / 160 = (21852 + 5 * x) / 8

Typedef Documentation

typedef struct sBSP430onewireBus sBSP430onewireBus

Structure identifying 1-wire bus information.

typedef struct sBSP430onewireSerialNumber sBSP430onewireSerialNumber

Structure holding a 1-wire serial number.

Enumeration Type Documentation

anonymous enum

Enumerator
BSP430_ONEWIRE_CMD_READ_ROM	Read 64-bit ROM code without using search procedure
BSP430_ONEWIRE_CMD_SKIP_ROM	Skip ROM sends the following command to all bus devices
BSP430_ONEWIRE_CMD_READ_POWER_SUPPLY	Determine whether device is parasite-powered or external-powered
BSP430_ONEWIRE_CMD_RECALL_EE	Store data from EEPROM into RAM
BSP430_ONEWIRE_CMD_READ_SCRATCHPAD	Read the RAM area.
BSP430_ONEWIRE_CMD_CONVERT_T	Initiate a temperature conversion. Be aware that temperature conversion can take up to 750ms at the default 12-bit resolution. For an externally (non-parasite) powered sensor, the caller may use iBSP430onewireReadBit_ni to determine whether the conversion has completed. Completion is indicated when the device responds with a 1.

Function Documentation

int iBSP430onewireComputeCRC	(	const unsigned char *	data,
		int	len
	)

Calculate the CRC over the data.

When the last byte of the data is the CRC of the preceding bytes, the return value of this function should be zero.

Parameters

data	data for which CRC is desired
len	the number of bytes that contribute to CRC calculation

Returns: the calculated CRC value

int iBSP430onewireReadBit_ni ( const sBSP430onewireBus * bus )

Read a bit from the 1-wire bus.

Parameters

bus	The port and bit identifying the 1-wire bus

Returns: The value of the bit read (0 or 1).

Examples:: sensors/ds18b20/main.c.

int iBSP430onewireReadByte_ni ( const sBSP430onewireBus * bus )

Read a byte from the 1-wire bus.

Invokes iBSP430onewireReadBit_ni eight times to read the data, least significant bit first.

Parameters

bus	The port and bit identifying the 1-wire bus

Returns: The value of the byte read (0 to 255).

int iBSP430onewireReadPowerSupply ( const sBSP430onewireBus * bus )

Determine whether device is externally powered or uses parasite power.

Parameters

bus	The port and bit identifying the 1-wire bus

Returns: 1 if the bus is externally powered; 0 if the bus is parasitically powered; a negative value if an error is encountered.

Examples:: sensors/ds18b20/main.c.

int iBSP430onewireReadSerialNumber	(	const sBSP430onewireBus *	bus,
		sBSP430onewireSerialNumber *	snp
	)

Read the serial number from a 1-wire device.

Parameters

bus	The port and bit identifying the 1-wire bus
snp	Pointer to where the serial number should be stored

Returns: 0 if the serial number was successfully read; -1 if an error occurred.

Examples:: sensors/ds18b20/main.c.

int iBSP430onewireReadTemperature_ni	(	const sBSP430onewireBus *	bus,
		int *	temp_xCel
	)

Read the most recent temperature measurement

The temperature is a signed 16-bit value representing 1/16th degrees Celcius. I.e., a value of 1 is 0.0625 Cel.

Note: The accuracy and precision of the measurement are much more coarse than its resolution.

Parameters

bus	The port and bit identifying the 1-wire bus
temp_xCel	Pointer to a location into which the temperature will be written. This must not be null.

Returns: 0 if the read was successful; -1 if an error occurred. If there was an error, the value pointed to by temp_xCel remains unchanged.

Examples:: sensors/ds18b20/main.c.

int iBSP430onewireRequestTemperature_ni ( const sBSP430onewireBus * bus )

Send the command sequence to initiate a temperature measurement

Note that this simply requests that the device start to measure the temperature. The measurement process may take up to 750 msec at the default 12-bit resolution.

If the device is externally powered, iBSP430onewireTemperatureReady_ni() can be invoked to determine whether the requested measurement has completed. If using parasitic power, the application should wait for at least the maximum sample time before invoking iBSP430onewireReadTemperature_ni().

Parameters

bus	The port and bit identifying the 1-wire bus

Returns: 0 if the request was successfully submitted, -1 if an error occured.

Examples:: sensors/ds18b20/main.c.

int iBSP430onewireReset_ni ( const sBSP430onewireBus * bus )

Reset the bus and check for device presence.

This executes the 1-wire bus reset protocol, then detects whether a 1-wire device is present. The protocol requires that the bus be held low for a given period, then returns it to pullup input. A device present on the bus will respond by pulling the bus low.

Parameters

bus	The port and bit identifying the 1-wire bus

Returns: 0 if no device was detected, 1 if a device responded to the reset.

static BSP430_CORE_INLINE int iBSP430onewireTemperatureReady_ni ( const sBSP430onewireBus * bus )

static

Test whether the device has completed measuring the temperature

Parameters

bus	The port and bit identifying the 1-wire bus

Note: Do not invoke this for parasitically-powered devices. See iBSP430onewireRequestTemperature_ni().

Returns: 0 if the device is still busy; 1 if the sample is ready.

void vBSP430onewireShutdown_ni ( const sBSP430onewireBus * bus )

Configure the bus pin for low power mode.

This reconfigures the port as output low. Note that this affects the MCU power, not the device power. It does remove power from parasitic devices, but externally powered devices will still draw some amount of current.

Parameters

bus	The port and bit identifying the 1-wire bus

Examples:: sensors/ds18b20/main.c.

void vBSP430onewireWriteByte_ni	(	const sBSP430onewireBus *	bus,
		int	byte
	)

Write a byte onto the 1-wire bus.

Parameters

bus	The port and bit identifying the 1-wire bus
byte	The value to be written. The low 8 bits are transmitted LSB-first.

Data Structures

Macros

Typedefs

Enumerations

Functions

Detailed Description

Macro Definition Documentation

Typedef Documentation

Enumeration Type Documentation

Function Documentation