EPC635 datasheet(27/97 Pages) EPC

27 / 97 page

Figure 24: Single-byte Read access through I2C

During a multi-byte read operation the master transmits the device address and the address of the first register to be read. After the

epc635 is addressed with a read command, epc635 answers with read data bytes until the master does not acknowledge a byte. The mas -

ter is expected to terminate the access with a STOP condition thereafter (Figure 25). During the access the read address pointer is incre-

mented epc635 internally. It is illegal to read so many data bytes that the read address pointer reaches the limit of reserved address space

(see chapter 8.4., Table 40, Table 41).

Figure 25: Multi-byte Read access through I2C

5.4.7. Control commands

The operating modes of the epc635 are initialized, activated, deactivated and monitored by sending several single or multi-byte write and

read command sequences through I2C interface. This section lists and explains all available commands together with their access times

(fSCL = 1MHz → tSCL = 1µs).

Listed in Table 13 is a summary of main control command sequences to operate the chip including the total number of command bytes

transferred and their duration. There is no particular order defined for sending the commands. The only requirement is having no on-going

frame acquisition process in the pipe when updating non-shadowed registers. The shadowed registers (marked with ** in the register map

e.g.INTM_hi/lo, Int_len_hi/lo, etc,. see section 8.4., Table 41) can be updated on-the-fly during a frame acquisition. New values are taken

into account by the next frame. The more safe approach would be finishing the last frame acquisition completely, only then update regis-

ters or change mode of operations.

Command

Description

Length

[Bytes]

Time

[µs]

Reset

I2C soft reset of the chip (same effect like the RESET pin)

Device address activation

I2C device address activation, see chapter 5.4.4

Single-byte Write

I2C Single-byte write to control registers

Multiple-byte Write

I2C Multiple-byte write (n bytes) to control registers

2 + n

20 + n x 9

Single-byte Read

I2C Single-byte read from control registers

Multiple-byte Read

I2C Multiple-byte read (n bytes) from control registers

3 + n

30 + n x 9

Mode set

Sine mode 4, 2, or 1 DCS set using MOD_control registers

Integration time (short) set

Integration time set (up to 800µs) using Int_len_hi/lo registers

Integration time (long) set

Integration time set (up to 26s) using INTM_hi/lo, Int_len_hi/lo registers

Dual Integration time (long) set

Dual int. time set using Int_len_mgx1_*, INTM_*, Int_len_* registers

Shutter

Soft shutter using Shutter_control registers (shutter_en bit)

Integration time (short) + Shutter

Int. time + soft shutter in one go! (Int_len_*, Shutter_control registers)

EEPROM Indirect Single Write

Indirect single write to EEPROM (bypass control registers)

20ms

EEPROM Direct Burst Write

Direct byte burst write (n bytes) to EEPROM (bypass control registers)

8 + n

n x 20ms

EEPROM Indirect Single Read

Indirect single read from EEPROM (bypass control registers)

EEPROM Direct Burst Read

Direct byte burst read (n bytes) from EEPROM (bypass control registers)

8 + n

78 + n x 9

Table 13: I2C Control commands summary

Characteristics subject to change without notice

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Datasheet_epc635-V1.02

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