ZHCU032K 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
数字滤波器输出的位数取决于过采样率,其范围为 15 至 30 位。图 27-5为每个 OSR,LSBACC,和 SD24UNI 设置给出了数字滤波器输出以及滤波器与 SD24MEMx 的关系。例如,对于 OSR= 1024,LSBACC= 0,和 SD24UNI= 1,SD24MEMx 寄存器包含数字滤波器输出的位 28 至位 13。当 OSR =32 时,一个 (SD24UNI= 0) 或 2 个 LSB (SD24UNI= 1) 始终为零。
SD24LSBACC 和 SD24LSBTOG 位给出了数字滤波器输出的最少有效位的访问权限。当 SD24LSBACC=1 时,通过使用字指令,数字滤波器的输出端的 16 个最低有效位可被 SD24MEMx 读取。通过只返回数字滤波器输出的 8 个最低有效位,可以用字节指令访问 SD24MEMx 寄存器。
当 SD24LSBTOG= 1 时,每次读取 SD24MEMx 都会自动切换 SD24LSBACC 位。这就使得完整的数字滤波器的输出结果被 SD24MEMx 的两次读取所读取。直到下一个 SD24MEMx 开始访问,设置或清零 SD24LSBTOG 才会改变 SD24LSBACC。