米6体育平台手机版

ZHCSIJ3C June 2008 – July 2018 ADS7950 , ADS7951 , ADS7952 , ADS7953 , ADS7954 , ADS7955 , ADS7956 , ADS7957 , ADS7958 , ADS7959 , ADS7960 , ADS7961

PRODUCTION DATA.

8.5.3 Alarm Thresholds for GPIO Pins

Each channel has two alarm program registers, one for setting the high alarm threshold and the other for setting the low alarm threshold. For ease of programming, two alarm programming registers per channel, corresponding to four consecutive channels, are assembled into one group (a total eight registers). There are four such groups for 16 channel devices and 3/2/1 such groups for 12/8/4 channel devices respectively. The grouping of the various channels for each device in the ADS79xx family is listed in Table 12. The details regarding programming the alarm thresholds are illustrated in the flowchart in Figure 59. Table 13 lists the details regarding the Alarm Program Register settings.

Table 12. Grouping of Alarm Program Registers

GROUP NO.	REGISTERS	APPLICABLE FOR DEVICE
0	High and low alarm for channel 0, 1, 2, and 3	ADS7953..50, ADS7957..54, ADS7961..58
1	High and low alarm for channel 4, 5, 6, and 7	ADS7953..51, ADS7957..55, ADS7961..59
2	High and low alarm for channel 8, 9, 10, and 11	ADS7953 and 52, ADS7957 and 56, ADS7961 and 60
3	High and low alarm for channel 12, 13, 14, and 15	ADS7953, ADS7957, ADS7961

Each alarm group requires 9 CS frames for programming their respective alarm thresholds. In the first frame the device enters the programming sequence and in each subsequent frame it programs one of the registers from the group. The device offers a feature to program less than eight registers in one programming sequence. The device exits the alarm threshold programming sequence in the next frame after it encounters the first ‘Exit Alarm Program’ bit high.

ADS7950 ADS7951 ADS7952 ADS7953 ADS7954 ADS7955 ADS7956 ADS7957 ADS7958 ADS7959 ADS7960 ADS7961 gpio_data_las605.gif

NOTE:

The device continues its operation in selected mode during programming. SDO is valid, however it is not possible to change the range or write GPIO data into the device during programming.

Figure 59. Alarm Program Register Programming Flowchart

Table 13. Alarm Program Register Settings

BITS	RESET STATE	LOGIC STATE	FUNCTION
FRAME 1
DI15-12	NA	1100	Device enters ‘alarm programming sequence’ for group 0
		1101	Device enters ‘alarm programming sequence’ for group 1
		1110	Device enters ‘alarm programming sequence’ for group 2
		1111	Device enters ‘alarm programming sequence’ for group 3
Note: DI15-12 = 11bb is the alarm programming request for group bb. Here ‘bb’ represents the alarm programming group number in binary format.
DI11-14	NA	Do not care
FRAME 2 AND ONWARDS
DI15-14	NA	cc	Where “cc” represents the lower two bits of the channel number in binary format. The device programs the alarm for the channel represented by the binary number “bbcc”. “bb” is programmed in the first frame.
DI13	NA	1	High alarm register selection
DI13	NA	0	Low alarm register selection
DI12	NA	0	Continue alarm programming sequence in next frame
DI12	NA	1	Exit Alarm Programming in the next frame. Note: If the alarm programming sequence is not terminated using this feature then the device will remain in the alarm programming sequence state and all SDI data will be treated as alarm thresholds.
DI11-10	NA	xx	Do not care
DI09-00	All ones for high alarm register and all zeros for low alarm register	This 10-bit data represents the alarm threshold. The 10-bit alarm threshold is compared with the upper 10-bit word of the 12-bit conversion result. The device sets off an alarm when the conversion result is higher (High Alarm) or lower (Low Alarm) than this number. For 10-bit devices, all 10 bits of the conversion result are compared with the set threshold. For 8-bit devices, all 8 bits of the conversion result are compared with DI09 to DI02 and DI00, 01 are 'do not care'.