ADBMS2950BCCSZ datasheet(64/97 Pages) AD

64 / 97 page

ADBMS2950B

Data Sheet

Rev. 0 | Page 64 of 97

SPI Controller Parameter

Timing Relationship to Primary SPI

Timing Specifications at tCLK = 0.5 µs

CSBM Falling to SCKM Rising

tCLK + t3

Min 0.6 µs

SCKM Falling to SDIOM, SDOM Valid

Controller requires < tCLK

When using the isoSPI, t4 is generated internally and is a minimum of 30 ns. Also, t3 = tCLK − t4. When using the SPI, t3, and t4 are the low and high times of the SCK input, each

with a specified minimum of 100 ns.

Table 86. I2C Controller Timing

I2C Controller Parameter

Timing Relationship to Primary SPI

Timing Specification at tCLK = 0.5 µs

SCL Clock Frequency

1 ÷ (2 × tCLK)

Max 1 MHz

tHD;STA

Min 100 ns

tLOW

tCLK

Min 0.5 µs

tHIGH

tCLK

Min 0.5 µs

tSU;STA

tCLK

+ t14

Min 0.53 µs

tHD;DAT

Min 30 ns

tSU;DAT

Min 100 ns

tSU;STO

tCLK

+ t14

Min 0.53 µs

tBUF

3 × tCLK

Min 1.5 µs

When using the isoSPI, t4 is generated internally and is a minimum of 30 ns. Also, t3 = tCLK − t4. When using the SPI, t3, and t4 are the low and high times of the SCK input, each

with a specified minimum of 100 ns.

SPI Sequence Example

The following steps are required to write and read any number

of bytes to an SPI peripheral connected to the ADBMS2950B:

1. Ensure that GPIOs/GPOs used for SPI transactions

are not actively forced low through CFGA, CFGB

default GPIO2 is not used, the alternative CS must be

manually asserted through CFGA.

2. Write data and control action through WRCOMM.

3. Perform transmission through STCOMM: 4 bytes for

command PEC and 3 bytes per byte to be transmitted,

maximum 9 bytes, independent of the length of the

daisy-chain as all ICs of the daisy-chain perform the

transmission simultaneously (no daisy-chain shift

not care, for example, it can be set to all 0x00.

4. Get data received during transmission through

RDCOMM if required (for example, not needed if

data is written to the peripheral only).

5. Continue with step 2 for any additional bytes.

The following is an example for writing 5 bytes (0xA1, 0xB2,

0xC3, 0xD4, 0xE5) and reading back all bytes received during

the transaction on the SDI input pin:

1. Write data and control action through WRCOMM.

ICOM0 = 0x8 (CS low), FCOM0 = 0x0 (hold CS low)

ICOM1 = 0x8 (CS low), FCOM1 = 0x0 (hold CS low)

ICOM2 = 0x8 (CS low), FCOM2 = 0x0 (hold CS low)

DATA0 = 0xA1, DATA1 = 0xB2, DATA2 = 0xC3

2. Perform transmission through STCOMM.

STCOMM (4 bytes for command PEC) followed by 9

bytes.

3. Get data received during transmission through

RDCOMM.

DATA0 (SDI byte 0), DATA1 (SDI byte 1), DATA2

(SDI byte 2).

4. Write data and control action via WRCOMM for the

last two remaining bytes.

ICOM0 = 0x8 (CS low), FCOM0 = 0x0 (hold CS low)

ICOM1 = 0x8 (CS low), FCOM1 = 0x9 (transmit

CSBM high after byte transmission)

ICOM2 = 0xF (no transit), FCOM2 = 0x9

DATA0 = 0xD4, DATA1 = 0xE5, DATA2 = 0xFF (3rd

byte is do not care)

5. Perform transmission through STCOMM.

STCOMM (4 bytes for CMD+PEC) followed by 6

bytes to transmit 2 bytes to the SPI peripheral only. It

is also possible to send 9 bytes to keep the STCOMM

common independent of number of bytes to be

transmitted as the ICOM/FCOM registers define

when to stop the transaction.

6. Get received data during transmission via RDCOMM.

DATA0 (SDI byte 3), DATA1 (SDI byte 4)

If several SPI peripherals are connected, whenever the default

CSBM is not used, the host must select the peripheral through

WRCFGA asserting the desired GPOx (CS of the peripheral)

before sending the COMM commands. ICOMx and FCOMx

must be set to 0x9 (instead of 0x8 and 0x0) for any byte to be

transmitted, and the SPI sequence is terminated with a final

WRCFGA de-asserting the used GPOx.

I2C Sequence Example

The following steps are required to write and read any number

of bytes to an I2C peripheral connected to the ADBMS2950B:

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