SLAU144K December 2004 – August 2022 MSP430AFE221 , MSP430AFE222 , MSP430AFE223 , MSP430AFE231 , MSP430AFE232 , MSP430AFE233 , MSP430AFE251 , MSP430AFE252 , MSP430AFE253 , MSP430F2001 , MSP430F2002 , MSP430F2003 , MSP430F2011 , MSP430F2012 , MSP430F2013 , MSP430F2101 , MSP430F2111 , MSP430F2112 , MSP430F2121 , MSP430F2122 , MSP430F2131 , MSP430F2132 , MSP430F2132-EP , MSP430F2232 , MSP430F2234 , MSP430F2252 , MSP430F2252-Q1 , MSP430F2254 , MSP430F2272 , MSP430F2272-Q1 , MSP430F2274 , MSP430F2274-EP , MSP430F233 , MSP430F2330 , MSP430F235 , MSP430F2350 , MSP430F2370 , MSP430F2410 , MSP430F2416 , MSP430F2417 , MSP430F2418 , MSP430F2419 , MSP430F247 , MSP430F2471 , MSP430F248 , MSP430F2481 , MSP430F249 , MSP430F2491 , MSP430F2616 , MSP430F2617 , MSP430F2618 , MSP430F2619 , MSP430G2001 , MSP430G2101 , MSP430G2102 , MSP430G2111 , MSP430G2112 , MSP430G2121 , MSP430G2131 , MSP430G2132 , MSP430G2152 , MSP430G2153 , MSP430G2201 , MSP430G2201-Q1 , MSP430G2202 , MSP430G2203 , MSP430G2210 , MSP430G2211 , MSP430G2212 , MSP430G2213 , MSP430G2221 , MSP430G2230 , MSP430G2231 , MSP430G2231-Q1 , MSP430G2232 , MSP430G2233 , MSP430G2252 , MSP430G2253 , MSP430G2302 , MSP430G2303 , MSP430G2312 , MSP430G2313 , MSP430G2332 , MSP430G2333 , MSP430G2352 , MSP430G2353 , MSP430G2402 , MSP430G2403 , MSP430G2412 , MSP430G2413 , MSP430G2432 , MSP430G2433 , MSP430G2444 , MSP430G2452 , MSP430G2453 , MSP430G2513 , MSP430G2533 , MSP430G2544 , MSP430G2553 , MSP430G2744 , MSP430G2755 , MSP430G2855 , MSP430G2955 , MSP430TCH5E
The analog input of each channel is configured using the SD24INCTLx register. These settings can be independently configured for each SD24_A channel.
The SD24INCHx bits select one of eight differential input pairs of the analog multiplexer. The gain for each PGA is selected by the SD24GAINx bits. A total of six gain settings are available.
On some devices SD24AEx bits are available to enable or disable the analog input pin. Setting any SD24AEx bit disables the multiplexed digital circuitry for the associated pin. See the device-specific data sheet for pin diagrams.
During conversion any modification to the SD24INCHx and SD24GAINx bits will become effective with the next decimation step of the digital filter. After these bits are modified, the next three conversions may be invalid due to the settling time of the digital filter. This can be handled automatically with the SD24INTDLYx bits. When SD24INTDLY = 00h, conversion interrupt requests will not begin until the fourth conversion after a start condition.
On devices implementing the high impedance input buffer it can be enabled using the SD24BUFx bits. The speed settings are selected based on the SD24_A modulator frequency as shown in Table 27-1.
SD24BUFx | Buffer | SD24 Modulator Frequency, fM |
---|---|---|
00 | Buffer disabled | |
01 | Low speed/current | fM < 200 kHz |
10 | Medium speed/current | 200 kHz < fM < 700 kHz |
11 | High speed/current | 700 kHz < fM < 1.1 MHz |
An external RC anti-aliasing filter is recommended for the SD24_A to prevent aliasing of the input signal. The cutoff frequency should be less than 10 kHz for a 1-MHz modulator clock and OSR = 256. The cutoff frequency may set to a lower frequency for applications that have lower bandwidth requirements.