ADM1034 datasheet(15/40 Pages) AD

15 / 40 page

ADM1034

Rev. 0 | Page 15 of 40

READ OPERATIONS

Receive Byte

This is useful when repeatedly reading a single register. The

to read a single byte. In this operation, the master device

receives a single byte from a slave device as follows:

The master device asserts a start condition on SDA.

The master sends the 7-bit slave address followed by the

read bit (high).

The addressed slave device asserts ACK on SDA.

The master receives a data byte.

The master sends NO ACK on SDA.

The master asserts a stop condition on SDA, and the

transaction ends.

In the ADM1034, the receive-byte protocol is used to read a

single byte from a register whose address has previously been

set by a send-byte or write-byte operation.

SLAVE

ADDRESS

DATA

R A

A P

Figure 24. Receive Byte

Block Read

In this operation, the master reads a block of data from a slave

device. The number of bytes to be read must be set in advance.

To do this, use a write-byte operation to the #Bytes/Block Read

whether a block-read or a read-byte operation is to be completed

(set MSB to 1 to specify a block-read operation). A maximum of

32 bytes can be read.

The master asserts a start condition on SDA.

The master sends the 7-bit slave address followed by the

write bit (low).

The addressed slave device asserts ACK on SDA.

The master sends the register address (MSB = 1).

The slave asserts ACK on SDA.

The master asserts a repeated start on SDA.

The master sends the 7-bit slave address followed by the

read bit (high).

The slave asserts ACK on SDA.

The slave sends the byte count.

10. The master asserts ACK on SDA.

11. The slave sends N data bytes.

12. The master asserts ACK on SDA after each data byte.

13. The master does not acknowledge after the Nth data byte.

14. The master asserts a stop condition on SDA to end the

transaction.

SLAVE

ADDRESS

BYTE

COUNT

DATA 1

ADDRESS

W A

A DATA N

SLAVE

ADDRESS

R A

Figure 25. Block Read from RAM

SMBus TIMEOUT

The ADM1034 has a programmable SMBus timeout feature.

When this is enabled, the SMBus typically times out after 25 ms

of no activity. The timeout is disabled by default. It prevents

hangups by releasing the bus after a period of inactivity.

To enable the SDA timeout, set the SDA timeout bit (Bit 5) of

Configuration Register 1 (Address 0x01) to 1.

To enable the SCL timeout, set the SCL timeout bit (Bit 4) of

Configuration Register 1 (Address 0x01) to 1.

PACKET ERROR CHECKING (PEC)

The ADM1034 also supports packet error checking (PEC). This

optional feature is triggered by the extra clock for the PEC byte.

The PEC byte is calculated using CRC-8. The frame check

sequence (FCS) conforms to CRC-8 by the following:

( )

For more information, consult www.SMBus.org.

ALERT RESPONSE ADDRESS (ARA)

ALERT RESPONSE

ADDRESS

DEVICE

ADDRESS

R A

A P

Figure 26. ALERT Response Address

When multiple devices exist on the same bus, the ARA feature

allows an interrupting device to identify itself to the host.

The ALERT output can be used as an interrupt output or as an

SMBusALERT. One or more ALERT outputs can be connected

to a common SMBusALERT line, connected to the master.

If a device’s ALERT line goes low, the following occurs:

SMBusALERT is pulled low.

The master initiates a receive-byte operation and sends the

alert response address (ARA 0001 100). This is a general

call address that must not be used as a specific address.

The device with the low ALERT output responds to the

ARA, and the master reads its device address. Once the

address is known, it can be interrogated in the usual way.

If low ALERT output is detected in more than one device,

the one with the lowest device address has priority, in

accordance with normal SMBus arbitration.

Once the ADM1034 has responded to the ARA, it resets its

ALERT output. However, if the error persists, the ALERT is

re-asserted on the next monitoring cycle.

ADM1034 数据表(PDF) 15 Page - Analog Devices

ADM1034 数据表(HTML) 15 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

数据表下载

链接网址

ADM1034 数据表(PDF) 15 Page - Analog Devices

ADM1034 数据表(HTML) 15 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

数据表 下载

链接网址

数据表下载