at94s40al ATMEL Corporation, at94s40al Datasheet - Page 6

• Manufacturer Part Number: at94s40al
• Description: At94s05al Secure 5k - 40k Gates Of At40k Fpga With 8-bit Microcontroller, Up To 36 Kbytes Of Sram And On-chip Program Storage Eeprom
• Manufacturer: ATMEL Corporation

4.5
4.6
4.7
Figure 4-1.
Table 4-1.
6
cSCK
cSDA
Where:R/W=1 Read
MSB
1st
1
Acknowledge Bit
Bit Ordering Protocol
Device Address Byte
AT94S Secure Family
= 0 Write
Start and Stop Conditions
Device Address Byte
Byte n
2nd
0
The Acknowledge (ACK) Bit shown in
byte. The receiving Configurator can accept the byte by asserting a Low value on the cSDA line,
or it can refuse the byte by asserting (allowing the signal to be externally pulled up to) a High
value on the cSDA line. All bytes from accepted messages must be terminated by either an
Acknowledge Bit or a Stop Condition. Following an ACK Bit, when the cSDA line is released dur-
ing an exchange of control between the Configurator and the programmer, the cSDA line may
be pulled High temporarily due to the open-collector output nature of the line. Control of the line
must resume before the next rising edge of the clock.
The most significant bit is the first bit of a byte transmitted on the cSDA line for the Device
Address Byte and the EEPROM Address Bytes. It is followed by the lesser significant bits until
the eighth bit, the least significant bit, is transmitted. However, for Data Bytes (both writing and
reading), the first bit transmitted is the least significant bit. This protocol is shown in the diagrams
below.
The contents of the Device Address Byte are shown below, along with the order in which the bits
are clocked into the device.
The CE pin cannot be used for device selection in programming mode (i.e., when SER_EN is
drive Low).
8th Bit
3rd
1
ACK BIT
Condition
4th
STOP
0
Figure 4-1
5th
0
t WR
is provided by the Configurator receiving the
6th
1
Condition
START
7th
1
2314E–FPSLI–6/05
LSB
R/W
8th