![](http://datasheet.mmic.net.cn/30000/MR80C52CXXX-20SCR_datasheet_2377250/MR80C52CXXX-20SCR_928.png)
928
32142D–06/2013
ATUC64/128/256L3/4U
Note:
1. These values are based on simulation and characterization of other AVR microcontrollers manufactured in the same pro-
cess technology. These values are not covered by test limits in production.
Maximum SPI Frequency, Slave Input Mode
The maximum SPI slave input frequency is given by the following formula:
Where
is the MOSI setup and hold time, SPI7 + SPI8 or SPI10 + SPI11 depending on
CPOL and NCPHA.
is the maximum frequency of the CLK_SPI. Refer to the SPI chap-
ter for a description of this clock.
Maximum SPI Frequency, Slave Output Mode
The maximum SPI slave output frequency is given by the following formula:
Where
is the MISO delay, SPI6 or SPI9 depending on CPOL and NCPHA.
is the
SPI master setup time. Please refer to the SPI master datasheet for
.
is the max-
imum frequency of the SPI pins. Please refer to the I/O Pin Characteristics section for the
maximum frequency of the pins.
35.10.5
TWIM/TWIS Timing
Figure 35-45 shows the TWI-bus timing requirements and the compliance of the device with
them. Some of these requirements (t
r and tf) are met by the device without requiring user inter-
vention. Compliance with the other requirements (t
HD-STA, tSU-STA, tSU-STO, tHD-DAT, tSU-DAT-TWI, tLOW-
TWI, tHIGH, and fTWCK) requires user intervention through appropriate programming of the relevant
Table 35-44. SPI Timing, Slave Mo
de Symbol
Parameter
Conditions
Min
Max
Units
SPI6
SPCK falling to MISO delay
VVDDIO from
3.0V to 3.6V,
maximum
external
capacitor =
40pF
29.4
ns
SPI7
MOSI setup time before SPCK rises
0
SPI8
MOSI hold time after SPCK rises
6.0
SPI9
SPCK rising to MISO delay
29.0
SPI10
MOSI setup time before SPCK falls
0
SPI11
MOSI hold time after SPCK falls
5.5
SPI12
NPCS setup time before SPCK rises
3.4
SPI13
NPCS hold time after SPCK falls
1.1
SPI14
NPCS setup time before SPCK falls
3.3
SPI15
NPCS hold time after SPCK rises
0.7
f
SPCKMAX
MIN f
CLKSPI
1
SPIn
------------
(,
)
=
SPIn
f
CLKSPI
f
SPCKMAX
MIN f
PINMAX
1
SPIn
t
SETUP
+
------------------------------------
(,
)
=
SPIn
t
SETUP
t
SETUP
f
PINMAX