The Stellaris Family of ARM® Cortex™-M3 microcontrollers features up to 2 hardware quadrature encoders enabling precise positioning sensing. A quadrature encoder input (QEI), also known as a 2-channel incremental encoder and most often used in motor control, converts linear displacement into a pulse signal. By monitoring both the number of pulses and the relative phase of the two signals, you can track the position, direction of rotation, and speed of a motor or apparatus. In addition, a third channel, or index signal, can be used to reset the position counter. Each QEI module interprets the code produced by a quadrature encoder wheel to integrate position over time and determine direction of rotation. In addition, it can capture a running estimate of the velocity of the encoder wheel.
| Flash (KB) | SRAM (KB) | Analog Comparators | ADC Channels | PWM Pins | Quadrature Encoder | |
|---|---|---|---|---|---|---|
| LM3S9L97 | 128 | 48 | 2 | 16 | 6 | 2 |
| LM3S9B96 | 256 | 96 | 3 | 16 | 8 | 2 |
| LM3S9B95 | 256 | 96 | 3 | 16 | 8 | 2 |
| LM3S9B92 | 256 | 96 | 3 | 16 | 8 | 2 |
| LM3S9997 | 256 | 64 | 2 | 16 | 6 | 2 |
| LM3S9792 | 128 | 64 | 3 | 16 | 8 | 2 |
| LM3S8971 | 256 | 64 | 1 | 8 | 6 | 1 |
| LM3S8962 | 256 | 64 | 1 | 4 | 6 | 2 |
| LM3S6965 | 256 | 64 | 2 | 4 | 6 | 2 |
| LM3S6952 | 256 | 64 | 3 | 3 | 4 | 1 |
| LM3S6950 | 256 | 64 | 3 | - | 6 | 1 |
| LM3S6753 | 128 | 64 | 2 | 4 | 6 | 1 |
| LM3S6610 | 128 | 32 | 3 | – | 4 | 1 |
| LM3S5Y36 | 16 | 8 | 2 | 8 | 6 | 1 |
| LM3S5T36 | 32 | 12 | 2 | 8 | 6 | 1 |
| LM3S5R36 | 256 | 48 | 2 | 8 | 8 | 1 |
| LM3S5R31 | 256 | 48 | 2 | 16 | 8 | 2 |
| LM3S5P56 | 64 | 24 | 2 | 8 | 6 | 1 |
| LM3S5P51 | 64 | 24 | 2 | 16 | 6 | 2 |
| LM3S5P36 | 64 | 24 | 2 | 8 | 6 | 1 |
| LM3S5P31 | 64 | 24 | 2 | 16 | 6 | 2 |
| LM3S5K36 | 128 | 24 | 2 | 8 | 6 | 1 |
| LM3S5K31 | 128 | 24 | 2 | 16 | 6 | 2 |
| LM3S5B91 | 256 | 96 | 3 | 16 | 8 | 2 |
| LM3S5956 | 256 | 64 | 2 | 8 | 6 | 1 |
| LM3S5951 | 256 | 64 | 2 | 16 | 6 | 2 |
| LM3S5791 | 128 | 64 | 3 | 16 | 8 | 2 |
| LM3S5656 | 128 | 32 | 2 | 8 | 6 | 1 |
| LM3S5651 | 128 | 32 | 2 | 16 | 6 | 2 |
| LM3S3749 | 128 | 64 | 2 | 8 | 8 | 1 |
| LM3S3748 | 128 | 64 | 2 | 8 | 8 | 1 |
| LM3S2B93 | 256 | 96 | 3 | 16 | 8 | 2 |
| LM3S2965 | 256 | 64 | 3 | 4 | 6 | 2 |
| LM3S2950 | 256 | 64 | 3 | – | 6 | 1 |
| LM3S2939 | 256 | 64 | 3 | 3 | 4 | 1 |
| LM3S2793 | 128 | 64 | 3 | 16 | 8 | 2 |
| LM3S2739 | 128 | 64 | 1 | 4 | 6 | 1 |
| LM3S2678 | 128 | 32 | – | 8 | 4 | 1 |
| LM3S2620 | 128 | 32 | 3 | – | 4 | 1 |
| LM3S2616 | 128 | 16 | 2 | 6 | 6 | 1 |
| LM3S1968 | 256 | 64 | 3 | 8 | 6 | 2 |
| LM3S1960 | 256 | 64 | 3 | - | 6 | 2 |
| LM3S1850 | 256 | 32 | 3 | - | 6 | 1 |
| LM3S1637 | 128 | 32 | 1 | 4 | 6 | 1 |
| LM3S1627 | 128 | 32 | – | 4 | 6 | 1 |
| LM3S1626 | 128 | 32 | – | 6 | 4 | 1 |
| LM3S1620 | 128 | 32 | 3 | - | 6 | 1 |
| LM3S1538 | 96 | 64 | - | 8 | - | 1 |
| LM3S1512 | 96 | 64 | 3 | 2 | - | 1 |
| LM3S1439 | 96 | 32 | 1 | 4 | 6 | 1 |
| LM3S1150 | 64 | 16 | 3 | - | 6 | 1 |
| LM3S818 | 64 | 8 | 1 | 6 | 6 | 1 |
| LM3S801 | 64 | 8 | 3 | – | 6 | 1 |
| LM3S618 | 32 | 8 | 1 | 6 | 6 | 1 |
| LM3S601 | 32 | 8 | 3 | – | 6 | 1 |