PIC12C508A-04I/P Microchip Technology, PIC12C508A-04I/P Datasheet - Page 33

• Manufacturer Part Number: PIC12C508A-04I/P
• Description: IC MCU OTP 512X12 8DIP
• Manufacturer: Microchip Technology
• Series: PIC® 12Cr

Specifications of PIC12C508A-04I/P

• Program Memory Type: OTP
• Program Memory Size: 768B (512 x 12)
• Package / Case: 8-DIP (0.300", 7.62mm)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 4MHz
• Peripherals: POR, WDT
• Number Of I /o: 5
• Ram Size: 25 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC12C
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 25 B
• Maximum Clock Frequency: 4 MHz
• Number Of Programmable I/os: 5
• Number Of Timers: 1
• Operating Supply Voltage: 2.5 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: DVMCPA, ICE2000
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: ISPICR1 - ADAPTER IN-CIRCUIT PROGRAMMINGDVMCPA - KIT DVR BOARD EVAL SYSTEM MXDEV1DVA12XP080 - ADAPTER DEVICE FOR MPLAB-ICEAC124001 - MODULE SKT PROMATEII 8DIP/SOIC
• Eeprom Size: -
• Data Converters: -
• Connectivity: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

7.3
7.3.1
Following the start signal from the master, the device
code (4 bits), the don’t care bits (3 bits), and the R/W
bit (which is a logic low) are placed onto the bus by the
master transmitter. This indicates to the addressed
slave receiver that a byte with a word address will follow
after it has generated an acknowledge bit during the
ninth clock cycle. Therefore, the next byte transmitted
by the master is the word address and will be written
into the address pointer. Only the lower four address
bits are used by the device, and the upper four bits are
don’t cares. The address byte is acknowledgeable and
the master device will then transmit the data word to be
written into the addressed memory location. The mem-
ory acknowledges again and the master generates a
stop condition. This initiates the internal write cycle,
and during this time will not generate acknowledge sig-
nals (Figure 7-7). After a byte write command, the inter-
nal address counter will not be incremented and will
point to the same address location that was just written.
If a stop bit is transmitted to the device at any point in
the write command sequence before the entire
sequence is complete, then the command will abort
and no data will be written. If more than 8 data bits are
transmitted before the stop bit is sent, then the device
will clear the previously loaded byte and begin loading
the data buffer again. If more than one data byte is
transmitted to the device and a stop bit is sent before a
full eight data bits have been transmitted, then the write
command will abort and no data will be written. The
EEPROM memory employs a V
circuit which disables the internal erase/write logic if the
V
Byte write operations must be preceded and immedi-
ately followed by a bus not busy bus cycle where both
SDA and SCL are held high.
FIGURE 7-7:
SDA LINE
BUS ACTIVITY
MASTER
BUS ACTIVITY
CC
X = Don’t Care Bit
1999 Microchip Technology Inc.
is below minimum VDD.
WRITE OPERATIONS
BYTE WRITE
S
T
A
R
T
S
BYTE WRITE
1
0
1
CONTROL
BYTE
0
CC
X
threshold detector
X
X
0
A
C
K
X
X
X
ADDRESS
WORD
X
7.4
Since the device will not acknowledge during a write
cycle, this can be used to determine when the cycle is
complete (this feature can be used to maximize bus
throughput). Once the stop condition for a write com-
mand has been issued from the master, the device ini-
tiates the internally timed write cycle. ACK polling can
be initiated immediately. This involves the master send-
ing a start condition followed by the control byte for a
write command (R/W = 0). If the device is still busy with
the write cycle, then no ACK will be returned. If no ACK
is returned, then the start bit and control byte must be
re-sent. If the cycle is complete, then the device will
return the ACK and the master can then proceed with
the next read or write command. See Figure 7-6 for
flow diagram.
FIGURE 7-6:
ACKNOWLEDGE POLLING
A
C
K
Initiate Write Cycle
Send Control Byte
Write Command
ACKNOWLEDGE POLLING
FLOW
with R/W = 0
Acknowledge
Condition to
Send Stop
(ACK = 0)?
Did Device
Send Start
Operation
Send
Next
PIC12C5XX
DATA
YES
DS40139E-page 33
NO
A
C
K
P
S
T
O
P