Datasheet
PGA280
SBOS487A –JUNE 2009–REVISED SEPTEMBER 2009................................................................................................................................................
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COMMAND STRUCTURE AND REGISTER OVERVIEW
Bit 7 is the most significant bit (MSB); bit 0 is the least significant bit (LSB). Binary numbers are denoted with 'b'.
'aaaa' is used to denote the encoded register pointer, 0000b to 1111b. 'T' denotes the buffer trigger bit. Writing to
unassigned bits is ignored, but it is recommend to write a '0' for all unassigned bits. PGA280 registers,
addresses, and functional information are summarized in the Register Map (Table 1).
Command Byte
01T0 aaaa dddd dddd: Write
Write 'dddd dddd' to internal PGA280 register at address aaaa
1000 aaaa 0000 0000: Read
Read from specified internal PGA280 register at address aaaa [no BUFT on read]. The number of trailing
zeros provides the clock for reading data. 16 SCLK pulses are required when reading the data byte plus
checksum.
00T0 aaaa:
Factory-reserved commands.
11T0 0ccc: Direct CS Command
Controls CS to pin (all pins are CS-capable, but not simultaneously; only one at a time) for ccc = 0 to 6,
corresponding to GPIO0 to GPIO6, if CS mode is activated.
Within the command byte, T = 1 triggers the current buffer (BUF). Each command is terminated with setting CS
to high; commands can be chained within a period of CS active low, but require a checksum byte, or a dummy
byte when checksum mode is disabled.
NOTE
BUF cannot be triggered during a read command.
Here are several examples (discrete commands):
Read Register 3:
Send 0x8300; response: 0xzz19 (this value is the initial setting of BUFTIM).
The first byte zz contains the line state (3-state) of SDO. The second byte is data.
NOTE
The PGA280 sends the CHKsum, if clocks are available while CS: Send 0x830000.
Response: 0xzz1937
Write Register 0:
Send 0x4018; set gain to 1V/V.
Write Register 4:
Send 0x44FF; reset all error flags.
Read Register 4:
Send 0x8400; response: 0xzz00 (no error flags set).
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