TMP1827 datasheet(34/65 Pages) TI

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9.4.3.3.5 WRITE SCRATCHPAD-2 (0Fh)

The function is issued by the host to prepare data write to the EEPROM using memory scratchpad.

Figure 9-23 shows that the host first sends 2 bytes for the EEPROM address, followed by 8 data bytes. On

receiving the 8 data bytes, the device computes the CRC for total of 10 bytes of address and data received

from the host for data integrity check. The function only copies the data to the memory scratchpad, to enable the

host to change data, before the final EEPROM erase and program. Additionally, the host may use the memory

scratchpad as a 8-byte volatile buffer.

The device does not support byte wise access for EEPROM. All access to the scratchpad are done in

increments of 8 bytes. Hence the host must send the address at the 8-byte block boundary. Figure 9-9 shows

that any attempt to write data at a non-block boundary will result in data corruption for the corresponding

EEPROM page and block.

9.4.3.3.6 READ SCRATCHPAD-2 (AAh)

The function is issued by the host to read the content of the memory scratchpad.

The host first sends the 2 bytes for the EEPROM address (see Figure 9-23). If the 2 bytes of address matches

the address sent during the last WRITE SCRATCHPAD-2, the device responds by sending the 8 bytes of data

that was written to the scratchpad-2 buffer earlier. The host can send a bus reset any time during the transfer. If

the device sends all 8 bytes and no bus reset is received,the device transmits the CRC computed on the 2 byte

of address sent by the host and 8 bytes of data sent by the device to the host for data integrity check.

If there is a mismatch in the EEPROM address, the device shall go back to the start and wait for a bus reset

to restart communication, and the host shall receive '1' on the bus for any subsequent read. This mechanism

ensures that the host can detect an address byte corruption during both WRITE SCRATCHPAD-2 and READ

SCRATCHPAD-2, as both the data bytes and CRC byte will read back as FFh.

9.4.3.3.7 COPY SCRATCHPAD-2 (55h)

The function is issued by the host to copy the contents of scratchpad-2 to the EEPROM. The EEPROM current

is higher during the erase and program, therefore the application must size the external pullup resistor to ensure

that there is sufficient current drawn by the one or more devices or implement a low impedance current path

using an external FET/transistor switch parallel to the bus pullup resistor.

The host application must ensure that only WRITE SCRATCHPAD-2 or READ SCRATCHPAD-2, with address of

the intended location in the user EEPROM, are issued before COPY SCRATCHPAD-2 is sent. The device stores

and uses the address sent during WRITE SCRATCHPAD-2 to identify the location in the user EEPROM where

the copy operation shall be performed. The host only needs to send one byte with A5h to initiate the copy of

the memory content from scratchpad-2 to the user EEPROM, at the address location already specified, when

performing the commit operation. The host must hold the bus in idle state for the EEPROM programming time

before starting any new access on the bus.

9.4.3.3.8 READ EEPROM (F0h)

The function is issued by the host to read the EEPROM memory directly.

The host sends 2 bytes for the address of the EEPROM location, that it wants to read. The device then

sends the data bytes starting from that location until the internal address pointer does not reach the end of

the EEPROM or host does not issue a bus reset. If the internal address pointer reaches end of the EEPROM

location, the device shall send 1's on the bus. After sending the 2 bytes for the address of the EEPROM location

to access, and when moving between block boundary, the host must idle the bus for tIDLE as specified in the

EEPROM characteristics. Additionally, there is no CRC provided in the response from the device during the

READ EEPROM function.

TMP1827

SBOSA15A – SEPTEMBER 2022 – REVISED MAY 2023

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