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 is configured using the SD16INCTL0 and the SD16AE registers. The SD16INCHx bits select one of eight differential input pairs of the analog multiplexer. The gain for the PGA is selected by the SD16GAINx bits. A total of six gain settings are available. The SD16AEx bits enable or disable the analog input pin. Setting any SD16AEx 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 SD16INCHx and SD16GAINx 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 SD16INTDLYx bits. When SD16INTDLY = 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 SD16BUFx bits. The speed settings are selected based on the SD16_A modulator frequency as shown in Table 26-1.
SD16BUFx | Buffer | SD16 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 SD16_A to prevent aliasing of the input signal. The cutoff frequency should be < 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.