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5.14 - SPI [U12 Datasheet]

Sends and receives data synchronously (SPI). First four bytes sent/received are passed in this call, and copied to the first 4 bytes of RAM buffer (first 4 bytes of RAM transmit buffer are never used). Any additional bytes must be written/read with the RAM. Baud rate with no delay is about 160 kpbs.

Table 5.14-1.

Command

 

Byte #

Description

0

Data Byte 3

1

Data Byte 2

2

Data Byte 1

3

Data Byte 0

4

Bit 7: ms Delay

 

Bit 6: Hundred ┬Ás Delay

 

Bits 5-4: XX

 

Bit 3: SPI Mode D

 

Bit 2: SPI Mode C

 

Bit 1: SPI Mode B

 

Bit 0: SPI Mode A

5

011XXX10 (SPI)

6

Number of bytes to write/read (1-18)

7

Bit 7: Control CS

 

Bit 6: State of Active CS

 

Bits 5-3: XXX

 

Bits 2-0: D line to use as CS (0-7)

 

 

Response

 

Byte #

Description

0

Data Byte 3

1

Data Byte 2

2

Data Byte 1

3

Data Byte 0

4

Bits 7-4: XXXX

 

Bit 3: CSStateTris Error Flag

 

Bit 2: SCKTris Error Flag

 

Bit 1: MISOTris Error Flag

 

Bit 0: MOSITris Error Flag

5

011XXX10 (Echo of byte 5)

6

Echo of byte 6 from Command

7

Echo of byte 7 from Command

LabJackPython Example

>>> import u12
>>> d = u12.U12(debug=True)
open called
Writing: [0x0, 0x0, 0x0, 0x0, 0x0, 0x57, 0x0, 0x0]
Received: [0x57, 0x0, 0x0, 0x0, 0xff, 0xff, 0x0, 0x0]
>>> d.rawSPI([1,2,3,4], NumberOfBytesToWriteRead = 4)
Writing: [0x4, 0x3, 0x2, 0x1, 0x1, 0x62, 0x4, 0x0]
Received: [0x4, 0x3, 0x2, 0x1, 0x1, 0x62, 0x4, 0x0]
{
'DataByte3': 4, 'DataByte2': 3, 'DataByte1': 2, 'DataByte0': 1,
'ErrorFlags':
<BitField object: [ CSStateTris Error Flag = 0 (0),
SCKTris Error Flag = 0 (0),
MISOTris Error Flag = 0 (0),
MOSITris Error Flag = 1 (1) ] >
}

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