7–14
Chapter 7: User Flash Memory in MAX V Devices
Software Support for UFM Block
■
■
Data transfer can be initiated only when the bus is free.
The data on the SDA line must be stable during the high period of the clock. The
high or low state of the data line can only change when the clock signal on the SCL
line is low.
■
Any transition on the SDA line while the SCL is high indicates a start or stop
condition.
Table 7–5 lists the ALTUFM_I2C megafunction input and output interface signals.
Table 7–5. ALTUFM_I2C Interface Signals
Pin
Description
Function
The bidirectional SDA port is used to transmit and receive serial data from the
UFM. The output stage of the SDA port is configured as an open drain pin to
perform the wired-ANDfunction.
SDA
SCL
WP
Serial Data/Address Line
The bidirectional SCL port is used to synchronize the serial data transfer to and
from the UFM. The output stage of the SCL port is configured as an open drain
pin to perform a wired-ANDfunction.
Serial Clock Line
Optional active high signal that disables the erase and write function for
read/write mode. The ALTUFM_I2C megafunction gives you an option to
protect the entire UFM memory or only the upper half of memory.
Write Protect
These inputs set the UFM slave address. The A6, A5, A4, A3 slave address bits
are programmable, set internally to 1010by default.
A
,
A
, A
0
Slave Address Input
2
1
START and STOP Condition
The master always generates start (S) and stop (P) conditions. After the start
condition, the bus is considered busy. Only a stop (P) condition frees the bus. The bus
stays busy if the repeated start (Sr) condition is executed instead of a stop condition.
In this occurrence, the start (S) and repeated start (Sr) conditions are functionally
identical.
A high-to-low transition on the SDA line while the SCL is high indicates a start
condition. A low-to-high transition on the SDA line while the SCL is high indicates a
stop condition. Figure 7–9 shows the start and stop conditions.
Figure 7–9. Start and Stop Conditions
SDA
SDA
SCL
SCL
P
S
Stop Condition
Start Condition
MAX V Device Handbook
January 2011 Altera Corporation
ALTERA [ ALTERA CORPORATION ]
