The XMEGA-B1 Xplained offers two sensors, a temperature sensor and a light sensor. In single-ended mode it can also measure two analog inputs, one from the on-board potentiometer and one from a source that is external to the board.
Temperature Sensor
The temperature sensor is made with a NTC resistor connected to PORTB on PB0. The output range on the network included the NTC is 0V – 1.1V (or 0V – 1/3VTG).NTC reference: NCP18WF104J03RB
The NTC range is -40°C to +125°C and the input voltage range is 1.047 V - 0.077 V for VTG = 3.3V.
| Temp (°C) | Value (kΩ) | Temp (°C) | Value (kΩ) | Temp (°C) | Value (kΩ) | Temp (°C) | Value (kΩ) |
|---|---|---|---|---|---|---|---|
| -30 | 2197.225 | 0 | 357.012 | 30 | 79.222 | 60 | 22.224 |
| -29 | 2055.558 | 1 | 338.006 | 31 | 75.675 | 61 | 21.374 |
| -28 | 1923.932 | 2 | 320.122 | 32 | 72.306 | 62 | 20.561 |
| -27 | 1801.573 | 3 | 303.287 | 33 | 69.104 | 63 | 19.782 |
| -26 | 1687.773 | 4 | 287.434 | 34 | 66.061 | 64 | 19.036 |
| -25 | 1581.881 | 5 | 272.500 | 35 | 63.167 | 65 | 18.323 |
| -24 | 1483.100 | 6 | 258.426 | 36 | 60.415 | 66 | 17.640 |
| -23 | 1391.113 | 7 | 245.160 | 37 | 57.797 | 67 | 16.986 |
| -22 | 1305.413 | 8 | 232.649 | 38 | 55.306 | 68 | 16.360 |
| -21 | 1225.531 | 9 | 220.847 | 39 | 52.934 | 69 | 15.760 |
| -20 | 1151.037 | 10 | 209.710 | 40 | 50.677 | 70 | 15.184 |
| -19 | 1081.535 | 11 | 199.196 | 41 | 48.528 | 71 | 14.631 |
| -18 | 1016.661 | 12 | 189.258 | 42 | 46.482 | 72 | 14.101 |
| -17 | 956.080 | 13 | 179.890 | 43 | 44.533 | 73 | 13.592 |
| -16 | 899.481 | 14 | 171.028 | 44 | 42.675 | 74 | 13.104 |
| -15 | 846.579 | 15 | 162.651 | 45 | 40.904 | 75 | 12.635 |
| -14 | 797.111 | 16 | 154.726 | 46 | 39.213 | 76 | 12.187 |
| -13 | 750.834 | 17 | 147.232 | 47 | 37.601 | 77 | 11.757 |
| -12 | 707.524 | 18 | 140.142 | 48 | 36.063 | 78 | 11.344 |
| -11 | 666.972 | 19 | 133.432 | 49 | 34.595 | 79 | 10.947 |
| -10 | 628.988 | 20 | 127.080 | 50 | 33.195 | 80 | 10.566 |
| -9 | 593.342 | 21 | 121.066 | 51 | 31.859 | 81 | 10.200 |
| -8 | 559.931 | 22 | 115.368 | 52 | 30.584 | 82 | 9.848 |
| -7 | 528.602 | 23 | 109.970 | 53 | 29.366 | 83 | 9.510 |
| -6 | 499.212 | 24 | 104.852 | 54 | 28.203 | 84 | 9.185 |
| -5 | 471.632 | 25 | 100.000 | 55 | 27.091 | 85 | 8.873 |
| -4 | 445.772 | 26 | 95.398 | 56 | 26.028 | 86 | 8.572 |
| -3 | 421.480 | 27 | 91.032 | 57 | 25.013 | 87 | 8.283 |
| -2 | 398.652 | 28 | 86.889 | 58 | 24.042 | 88 | 8.006 |
| -1 | 377.193 | 29 | 82.956 | 59 | 23.113 | 89 | 7.738 |
| Temp (°C) | Value (kΩ) | Temp (°C) | Value (kΩ) | Temp (°C) | Value (kΩ) | Temp (°C) | Value (kΩ) |
Light Sensor
The light sensor is made with a Light Dependant Resistor (LDR) connected to PORTB on PB2. The output range on the network included the LDR is 0V – 1.1V (or 0V – 1/3×VTG).
When the light level is low, the resistance of the LDR is high and the input voltage is close to 1.1V (or 1/3×VTG).
Potentiometer voltage
An external voltage can be applied to the kit by using a header as shown in Figure 3‑1. This voltage is routed to pin PB3 on the XMEGA PORTB and can be measured with a single ended measurement of the ADC. However, the external voltage is divided down by 8 before it is applied to the ADC, this divider is fixed.
External voltage input
The output of the on-board potentiometer can be measured on PORTB on PB1 as single ended. The input range is 0V – 0.666V (or 0V – 1/5×VTG).
A 2.0 V zener diode is mounted in parallel with the ADC input. This protects the ADC input from any overvoltage. That effectively means that an external voltage is allowed between 0V-16V on the premises that VTG is greater than 2.0 V.
If VTG is lower than 2.0 V, the ADC input is not protected and the External Voltage Input must be on the range 0V – 8 ×VTG. Otherwise, the device may be damaged.