AT21CS01 datasheet(30/47 Pages) MICROCHIP

30 / 47 page

Figure 7-5. Serial Number Read

SI/O

MSB

ACK

by Slave

1 A2 A1 A0 0

Device Address

MSB

Serial Number Starting Address

MSB

Serial Number Byte 00h

ACK

by Slave

ACK

by Master

Stop Condition

by Master

Start Condition

by Master

MSB

ACK

by Slave

1 A2 A1 A0 1

Device Address

Restart

by Master

MSB

Serial Number Byte 07h

Dummy Write

NACK

by Master

7.5

Manufacturer ID Read

The AT21CS01/11 offers the ability to query the device for manufacturer, density, and revision

information. By using a specific opcode and following the format of a current address read, the device will

return a 24-bit value that corresponds with the I2C identifier value reserved for Microchip, along with

further data to signify a 1-Kbit density and the device revision.

To read the Manufacturer ID data, the master must send a Start condition, followed by the device address

byte with the opcode of 1100b (Ch) specified, along the appropriate slave address combination and the

Read/Write bit set to a logic ‘1’. After the device address byte has been sent, the AT21CS01/11 will return

an ACK (logic ‘0’). If the Read/Write bit is set to a logic ‘0’ to indicate a write, the device will NACK (logic

‘1’) since the Manufacturer ID data is read-only.

After the device has returned an ACK, it will then send the first byte of Manufacturer ID data which

contains the eight Most Significant bits (D23

‑D16) of the 24-bit data value. The master can then return an

ACK (logic ‘0’) to indicate it successfully received the data, upon which the device will send the second

byte (D15

‑D8) of Manufacturer ID data. The process repeats until all three bytes have been read out and

the master sends a NACK (logic ‘1’) to complete the sequence. Figure 7-6 depicts this sequence below. If

the master ACKs (logic ‘0’) the third byte, the Internal Pointer will roll over back to the first byte of

Manufacturer ID data.

Figure 7-6. Manufacturer ID Read

SI/O

MSB

ACK

by Slave

0 A2 A1 A0 1

Device Address

MSB

(D23)

Manufacturer ID Byte 1

ACK

by Master

Manufacturer ID Byte 2

NACK

by Master

Stop Condition

by Master

Start Condition

by Master

ACK

by Master

LSB

(D0)

Manufacturer ID Byte 3

Table 7-2 below provides the format of the Manufacturer ID data.

Table 7-2. Manufacturer ID Data Format

Device

Manufacturer Code

<D23:D12>

Device Code

<D11:D3>

Revision Code

<D2:D0>

Hex Value

<D23:D0>

AT21CS01

0000-0000-1101

0010-0000-0

000

00D200h

AT21CS11

0000-0000-1101

0011-1000-0

000

00D380h

AT21CS01/AT21CS11

Datasheet

DS20005857A-page 30

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