RS08KA2 PROMO Freescale Semiconductor, RS08KA2 PROMO Datasheet - Page 23

• Manufacturer Part Number: RS08KA2 PROMO
• Description: DEMO KIT, SILICON BUNDLE, RS08KA2
• Manufacturer: Freescale Semiconductor

Specifications of RS08KA2 PROMO

• Kit Contents: DEMO9RS08KA2 Board, USB Cable, Quick Start Guide, User Manual, Packing List
• Svhc: No SVHC (15-Dec-2010)
• Development Tool Type: Demonstration Kit
• Kit Features: RS08KA2 Microcontroller,
• Silicon Manufacturer: Freescale
• Core Architecture: RS08
• Core Sub-architecture: RS08
• Silicon Core Number: MC9RS08
• Silicon Family Name: RS08KA
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Freescale Semiconductor
2. Define RC time constant. The RC charging profile follows
3. Construct the lookup table. Given the timer resolution, 4µs in this example, it is possible to
The capacitor charge level reaches 99% when the time, t, reaches about 4.6 times of the RC
constant. To maximize the measurement range, the timer overflow period is expected to be longer
than or equal to this value. In this example, with 1.02ms timer overflow period RC constant
becomes 2.21E-4.
The value of the resistor, R, is defined by the port sinking capability. Referring to the data sheet of
MC9RS08KA2, the sinking current can keep in around 1mA level so that the initial discharged
voltage level can maintain to be close to 0V. Assuming V
chosen. Then, given 2.21E-4 time constant, capacitor C becomes 47nF. Please note this sinking
current will contribute to the overall system I
before the MCU enters stop mode, it is recommended to configure the port back to input or high
impedance to avoid current leakage.
construct a lookup table to compensate for the nonlinearity of the charging profile based on
Equation
A linear ADC is expected to quantize the input voltage at step boundary starting from step/2 input
voltage as shown in
2. The step size for a linear 8-bit ADC is given as:
Figure
$03
$02
$01
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Figure 2-6. ADC Quantization Diagram
2-6. The conversion function becomes:
RC
Step/2
Getting Started with RS08, Rev. 1
=
V
Step
TimerOverflowPeriod
---------------------------------------------------------- -
=
Step
3*Step/2
V
DD
ADC in (V)
=
⎛
⎜
⎝
1 e
Step
4.61
V
--------- -
255
–
DD
DD
5*Step/2
–
------- -
RC
t
consumption. If the ADC function is not used, or
⎞
⎟
⎠
Step
7*Step/2
DD
Equation
of 5V is used, 4700Ω resistor R is
Emulated ADC Application Example
2.
Eqn. -2
Eqn. -3
Eqn. -4
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