Siemens AC75 manual Specifying Delay Time for I²C, 2 , Selecting SPI Mode

AC75 AT Command Set

19.8 AT^SSPI

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Subparameter	Bit		Hexadecimal	Selected function
SPI mode	D15	- D12	0	Four different SPI modes. Phase and
			1	polarity of all SPI modes are illustrated in
			2	Section 19.8.2, Selecting SPI Mode.
			3
Chip Select (CS) mode	D11	- D8	0	One Chip Select per Transfer Frame.
Arrangement of bytes	D7 - D4		0	Big endian
Bit sequence	D3 - D0		0	MSB first
(arrangement of bits on the SPI)

19.8.1Specifying Delay Time for I²C

The following figures are provided to assist you in specifying appropriate values for the parameters <delayOne> and <delayTwo>. All delays are relative to the data transfer rate. To calculate the delay use the formula and the values given below.

	Figure 19.1: Formula for calculating the delay
Table 19.2: Values for calculating the delay
Parameter	Values
Delay value	Value set with parameter <delayOne> or <delayTwo>
Master clock	13 MHz
Default data transfer rate	400 bps
User data transfer rate	Value selected with subparameter data transfer rate within <basicConfigura-
	tion>, for example 100 kbps or 400 kbps
Delay_min for Write	7.4 µs at 100 kbps
	2.0 µs at 400 kbps
Delay_min for Read	9.9 µs at 100 kbps
	2.6 µs at 400 kbps

Figure 19.2: Delay time on I²C after Write

AC75_ATC_V01.002	Page 498 of 569	10/30/06
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