Cypress PSoC 5 FIRSTTOUCH CY8CKIT-014, Руководство пользователя

Страница: 17 / 44

CY8CKIT-014 PSoC 5 FirstTouch Starter Kit Guide, Spec. # 001-57708 Rev. ** 17
Example Projects
Figure 4-7. PSoC Rocks SAR ADC Schematic
4.1.6 How the PSoC Rocks and PSoC Rocks SAR ADC Projects Work
This example displays a message using a bank of LEDs, that when swung in a back and forth arcing
motion, produces a rasterized character display. The PSoC 5 FirstTouch Starter Kit has a three axis
accelerometer. The accelerometer detects the instantaneous acceleration of the board when in
motion. The instantaneous voltage at each axis of the accelerometer is directly proportional to the
acceleration along that axis.
In this project, the firmware uses the Y axis voltage output of the accelerometer. This voltage is
routed to an ADC in the PSoC. This digital value is now a measure of acceleration detected by the
accelerometer. If the acceleration exceeds a maximum value it signals the start of a new wave event.
On start of a new wave the firmware delays for a fixed period of time to start the first character in the
proper position of the wave. The current string is converted into a rasterized display data array prior
to the start of the wave. Each column of the rasterized data array is sequentially output after a fixed
delay. The delay periods may be adjusted in firmware.
For a particular character in the message, a look up table determines which LEDs to turn on. When
the board is waved back and forth rapidly, due to persistence of vision, the user defined image
appears to float in the air. Multiple strings may be configured with each string being displayed for an
adjustable number of wave cycles.