Modbus - Real-Time Clock Bricklet 2.0

This is the description of the Modbus protocol for the Real-Time Clock Bricklet 2.0. General information and technical specifications for the Real-Time Clock Bricklet 2.0 are summarized in its hardware description.

API

A general description of the Modbus protocol structure can be found here.

Basic Functions

BrickletRealTimeClockV2.set_date_time
Function ID:

1

Request:
  • year -- uint16
  • month -- uint8
  • day -- uint8
  • hour -- uint8
  • minute -- uint8
  • second -- uint8
  • centisecond -- uint8
  • weekday -- uint8
Response:

no response

Sets the current date (including weekday) and the current time with hundredths of a second resolution.

Possible value ranges:

  • Year: 2000 to 2099
  • Month: 1 to 12 (January to December)
  • Day: 1 to 31
  • Hour: 0 to 23
  • Minute: 0 to 59
  • Second: 0 to 59
  • Centisecond: 0 to 99
  • Weekday: 1 to 7 (Monday to Sunday)

If the backup battery is installed then the real-time clock keeps date and time even if the Bricklet is not powered by a Brick.

The real-time clock handles leap year and inserts the 29th of February accordingly. But leap seconds, time zones and daylight saving time are not handled.

The following meanings are defined for the parameters of this function:

  • 1: monday, for weekday
  • 2: tuesday, for weekday
  • 3: wednesday, for weekday
  • 4: thursday, for weekday
  • 5: friday, for weekday
  • 6: saturday, for weekday
  • 7: sunday, for weekday
BrickletRealTimeClockV2.get_date_time
Function ID:

2

Request:

empty payload

Response:
  • year -- uint16
  • month -- uint8
  • day -- uint8
  • hour -- uint8
  • minute -- uint8
  • second -- uint8
  • centisecond -- uint8
  • weekday -- uint8
  • timestamp -- int64

Returns the current date (including weekday) and the current time of the real-time clock with hundredths of a second resolution.

The timestamp represents the current date and the the current time of the real-time clock converted to milliseconds.

The following meanings are defined for the parameters of this function:

  • 1: monday, for weekday
  • 2: tuesday, for weekday
  • 3: wednesday, for weekday
  • 4: thursday, for weekday
  • 5: friday, for weekday
  • 6: saturday, for weekday
  • 7: sunday, for weekday
BrickletRealTimeClockV2.get_timestamp
Function ID:

3

Request:

empty payload

Response:
  • timestamp -- int64

Returns the current date and the time of the real-time clock converted to milliseconds. The timestamp has an effective resolution of hundredths of a second.

Advanced Functions

BrickletRealTimeClockV2.set_offset
Function ID:

4

Request:
  • offset -- int8
Response:

no response

Sets the offset the real-time clock should compensate for in 2.17 ppm steps between -277.76 ppm (-128) and +275.59 ppm (127).

The real-time clock time can deviate from the actual time due to the frequency deviation of its 32.768 kHz crystal. Even without compensation (factory default) the resulting time deviation should be at most ±20 ppm (±52.6 seconds per month).

This deviation can be calculated by comparing the same duration measured by the real-time clock (rtc_duration) an accurate reference clock (ref_duration).

For best results the configured offset should be set to 0 ppm first and then a duration of at least 6 hours should be measured.

The new offset (new_offset) can be calculated from the currently configured offset (current_offset) and the measured durations as follow:

new_offset = current_offset - round(1000000 * (rtc_duration - ref_duration) / rtc_duration / 2.17)

If you want to calculate the offset, then we recommend using the calibration dialog in Brick Viewer, instead of doing it manually.

The offset is saved in the EEPROM of the Bricklet and only needs to be configured once.

BrickletRealTimeClockV2.get_offset
Function ID:

5

Request:

empty payload

Response:
  • offset -- int8

Returns the offset as set by set_offset.

BrickletRealTimeClockV2.get_spitfp_error_count
Function ID:

234

Request:

empty payload

Response:
  • error_count_ack_checksum -- uint32
  • error_count_message_checksum -- uint32
  • error_count_frame -- uint32
  • error_count_overflow -- uint32

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

BrickletRealTimeClockV2.set_bootloader_mode
Function ID:

235

Request:
  • mode -- uint8
Response:
  • status -- uint8

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following meanings are defined for the parameters of this function:

  • 0: bootloader, for mode
  • 1: firmware, for mode
  • 2: bootloader wait for reboot, for mode
  • 3: firmware wait for reboot, for mode
  • 4: firmware wait for erase and reboot, for mode
  • 0: ok, for status
  • 1: invalid mode, for status
  • 2: no change, for status
  • 3: entry function not present, for status
  • 4: device identifier incorrect, for status
  • 5: crc mismatch, for status
BrickletRealTimeClockV2.get_bootloader_mode
Function ID:

236

Request:

empty payload

Response:
  • mode -- uint8

Returns the current bootloader mode, see set_bootloader_mode.

The following meanings are defined for the parameters of this function:

  • 0: bootloader, for mode
  • 1: firmware, for mode
  • 2: bootloader wait for reboot, for mode
  • 3: firmware wait for reboot, for mode
  • 4: firmware wait for erase and reboot, for mode
BrickletRealTimeClockV2.set_write_firmware_pointer
Function ID:

237

Request:
  • pointer -- uint32
Response:

no response

Sets the firmware pointer for write_firmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

BrickletRealTimeClockV2.write_firmware
Function ID:

238

Request:
  • data -- uint8[64]
Response:
  • status -- uint8

Writes 64 Bytes of firmware at the position as written by set_write_firmware_pointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

BrickletRealTimeClockV2.set_status_led_config
Function ID:

239

Request:
  • config -- uint8
Response:

no response

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following meanings are defined for the parameters of this function:

  • 0: off, for config
  • 1: on, for config
  • 2: show heartbeat, for config
  • 3: show status, for config
BrickletRealTimeClockV2.get_status_led_config
Function ID:

240

Request:

empty payload

Response:
  • config -- uint8

Returns the configuration as set by set_status_led_config

The following meanings are defined for the parameters of this function:

  • 0: off, for config
  • 1: on, for config
  • 2: show heartbeat, for config
  • 3: show status, for config
BrickletRealTimeClockV2.get_chip_temperature
Function ID:

242

Request:

empty payload

Response:
  • temperature -- int16

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

BrickletRealTimeClockV2.reset
Function ID:243
Request:empty payload
Response:no response

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

BrickletRealTimeClockV2.write_uid
Function ID:

248

Request:
  • uid -- uint32
Response:

no response

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

BrickletRealTimeClockV2.read_uid
Function ID:

249

Request:

empty payload

Response:
  • uid -- uint32

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

BrickletRealTimeClockV2.get_identity
Function ID:

255

Request:

empty payload

Response:
  • uid -- char[8]
  • connected_uid -- char[8]
  • position -- char
  • hardware_version -- uint8[3]
  • firmware_version -- uint8[3]
  • device_identifier -- uint16

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c' or 'd'.

The device identifier numbers can be found here

Callback Configuration Functions

BrickletRealTimeClockV2.set_date_time_callback_configuration
Function ID:

6

Request:
  • period -- uint32
Response:

no response

Sets the period in ms with which the CALLBACK_DATE_TIME callback is triggered periodically. A value of 0 turns the callback off.

The default value is 0.

BrickletRealTimeClockV2.get_date_time_callback_configuration
Function ID:

7

Request:

empty payload

Response:
  • period -- uint32

Returns the period as set by set_date_time_callback_configuration.

BrickletRealTimeClockV2.set_alarm
Function ID:

8

Request:
  • month -- int8
  • day -- int8
  • hour -- int8
  • minute -- int8
  • second -- int8
  • weekday -- int8
  • interval -- int32
Response:

no response

Configures a repeatable alarm. The CALLBACK_ALARM callback is triggered if the current date and time matches the configured alarm.

Setting a parameter to -1 means that it should be disabled and doesn't take part in the match. Setting all parameters to -1 disables the alarm completely.

For example, to make the alarm trigger every day at 7:30 AM it can be configured as (-1, -1, 7, 30, -1, -1, -1). The hour is set to match 7 and the minute is set to match 30. The alarm is triggered if all enabled parameters match.

The interval has a special role. It allows to make the alarm reconfigure itself. This is useful if you need a repeated alarm that cannot be expressed by matching the current date and time. For example, to make the alarm trigger every 23 seconds it can be configured as (-1, -1, -1, -1, -1, -1, 23). Internally the Bricklet will take the current date and time, add 23 seconds to it and set the result as its alarm. The first alarm will be triggered 23 seconds after the call. Because the interval is not -1, the Bricklet will do the same again internally, take the current date and time, add 23 seconds to it and set that as its alarm. This results in a repeated alarm that triggers every 23 seconds.

The interval can also be used in combination with the other parameters. For example, configuring the alarm as (-1, -1, 7, 30, -1, -1, 300) results in an alarm that triggers every day at 7:30 AM and is then repeated every 5 minutes.

The following meanings are defined for the parameters of this function:

  • -1: disabled, for month, day, hour, minute, second and weekday
  • -1: disabled, for interval
BrickletRealTimeClockV2.get_alarm
Function ID:

9

Request:

empty payload

Response:
  • month -- int8
  • day -- int8
  • hour -- int8
  • minute -- int8
  • second -- int8
  • weekday -- int8
  • interval -- int32

Returns the alarm configuration as set by set_alarm.

The following meanings are defined for the parameters of this function:

  • -1: disabled, for month, day, hour, minute, second and weekday
  • -1: disabled, for interval

Callbacks

BrickletRealTimeClockV2.CALLBACK_DATE_TIME
Function ID:

10

Response:
  • year -- uint16
  • month -- uint8
  • day -- uint8
  • hour -- uint8
  • minute -- uint8
  • second -- uint8
  • centisecond -- uint8
  • weekday -- uint8
  • timestamp -- int64

This callback is triggered periodically with the period that is set by set_date_time_callback_configuration. The response values are the same as for get_date_time.

The following meanings are defined for the parameters of this function:

  • 1: monday, for weekday
  • 2: tuesday, for weekday
  • 3: wednesday, for weekday
  • 4: thursday, for weekday
  • 5: friday, for weekday
  • 6: saturday, for weekday
  • 7: sunday, for weekday
BrickletRealTimeClockV2.CALLBACK_ALARM
Function ID:

11

Response:
  • year -- uint16
  • month -- uint8
  • day -- uint8
  • hour -- uint8
  • minute -- uint8
  • second -- uint8
  • centisecond -- uint8
  • weekday -- uint8
  • timestamp -- int64

This callback is triggered every time the current date and time matches the configured alarm (see set_alarm). The response values are the same as for get_date_time.

The following meanings are defined for the parameters of this function:

  • 1: monday, for weekday
  • 2: tuesday, for weekday
  • 3: wednesday, for weekday
  • 4: thursday, for weekday
  • 5: friday, for weekday
  • 6: saturday, for weekday
  • 7: sunday, for weekday