LM3S5G51 Datasheet, PDF (1006/1266 Pages) Texas Instruments – Stellaris® LM3S5G51 Microcontroller

Analog Comparators
Table 19-3. Internal Reference Voltage and ACREFCTL Field Values (continued)
ACREFCTL Register
EN Bit
Value
RNG Bit Value ^{Output Reference Voltage Based on VREF Field Value}
RNG=0 Total resistance in ladder is 31 R.
VIREF = VDDA × ^RVREF
EN=1
RNG=1
TTohte^VVVVV_VVVV^VV_VVVV^VV_VVVVV^VVVVV_alr^I_I^I_I^I_IIII^IIII_III^II_IIII^IIIIIar^RRR_RRRRRRRRR^RRRRRR_RRRR^RRRRR_enEEE^EEE_EEEEEEs^EEEEEE_EEEE^EEEEEgi^FFF_FFFFFFFFF^FFFFFFFFFFF_FFFFsetaonf⁼⁼⁼⁼⁼₌⁼⁼₌₌₌₌⁼⁼⁼⁼⁼_=======⁼⁼_=cinete^VV_VVVV^VVVVV_VVVVVV^VVVVV000_000000inrn^DDDDDD_D^D_D^D_D^D_D^D_DD^DD_DDDD^..._{......laaDDDDD}^DDDDD_D^DD_DDDD^DDDDD888₈₈₈₁₁₁ld_AAAAA^AAAAA_A^AAAAAAA_AAAArd₄₄₄⁵⁵⁵₅₅₅eef^{×××××}_{××××××}^××_{××××}^{×××××}e_333r r⁺⁺⁺_+++ise^V_VVVV^RRR_RRR^RRRRR(((((_{(×××}n2^VVVVV_Vc⁰⁰⁰₀₀₀^R_RRRR3^VVVVVVVV_VVV^RRRRRRRRRR₂₂₂₂e^RRRRR_RVVV^RRRRRRRR_RRR^..._...R^E_EEEE^TTTTTTTTTTTT₃₃₃₃i^EEEEEEEE_EEE^EEEEE_En_RRR.¹¹¹₁₁₁^F_FFFF^FFFFFFFF_FFF³³³³₃₃^FFFFF_Ft_EEEh⁰⁰⁰₀₀₀¹¹¹¹₁₁i_FFFs⁶⁶⁶₆₆₆⁺⁺⁺⁺⁺₊mo^×××_×××⁸⁸⁸⁸⁸₈de^VVV_VVV⁾⁾⁾⁾⁾₎is^RRR_RRR0^EEE_EEE.8^FFF_FFF5-2.448 V.
VIREF = V0D.D1A4×3 ^V×^R2V^E3R^FEF
VIREF = 0.143 ײV³REF
VIREF = 0.143 × VREF
19.4
The range of internal reference for this mode is 0-2.152 V.
Initialization and Configuration
The following example shows how to configure an analog comparator to read back its output value
from an internal register.
1. Enable the analog comparator clock by writing a value of 0x0010.0000 to the RCGC1 register
in the System Control module (see page 267).
2. Enable the clock to the appropriate GPIO modules via the RCGC2 register (see page 276). To
find out which GPIO ports to enable, refer to Table 23-5 on page 1143.
3. In the GPIO module, enable the GPIO port/pin associated with the input signals as GPIO inputs.
To determine which GPIO to configure, see Table 23-4 on page 1134.
4. Configure the PMCn fields in the GPIOPCTL register to assign the analog comparator output
signals to the appropriate pins (see page 464 and Table 23-5 on page 1143).
1006
Texas Instruments-Production Data
January 23, 2012