Renesas RX231, User Manual

Page: 15 / 34

Hear-it! Solution Kit 4 Hardware Design
R12UZ0012EG0110 Rev. 1.10 Page 15 of 34
Apr 03, 2017
4.2 Hardware Configuration
The Hear-it! Solution Kit hardware consists of the RX231 microcontroller and associated circuitry, a WM8983
CODEC IC, a USB Host connector, embedded E2-Lite programmer/debugger, PMOD
TM
connector and power
supply.
4.2.1 RX231 Microcontroller
The RX231 fitted to the Hear-it! PCB has the Renesas part number R5F52318ADFP. It is a 100pin LFQFP
package with 512kB Flash ROM, 64kB RAM and 8kB DataFlash. The 32-bit CPU can be clocked at up to 54MHz
and supports single precision floating point operations. The RX231 microcontroller incorporates extensive
supporting peripherals such as DMA, multiple timers, multiple communications functions such as SSI, SCI, I
2
C,
SPI, CAN, 12-bit ADC and DAC, capacitive touch-sensing.
The circuitry supporting the RX231 microcontroller consists of an 8MHz main oscillator, Real-Time-Clock
oscillator (RTC) (not fitted as standard), programmer/debugger connections and a potentiometer and switch for
user input.
4.2.2 Programmer/Debugger Connections
By default the Hear-it! board uses the embedded E2-Lite programmer/debugger to access the RX231
microcontroller. There is provision to fit a 14-way connector (Samtec part number SAM_HTST-107-01-X-DV) to
support connection of an external E1 or E2-Lite programmer/debugger if required. If an external debugger is
used, the embedded E2-Lite debugger must be deactivated by setting it to ‘standalone’ mode, achieved by
setting both switches in the switch block SW1 to the ‘OFF’ position, see Figure 4-2.
Figure 4-2 : Debugger Isolating Switch SW1 in “Off” Position
4.2.3 User Controls
Inputs from the user are taken from the potentiometer R43, for up and down menu control and switch SW3, for
user selection. The potentiometer is read on the MCU’s ADC channel 0 (P4-0, pin 95). The reading, as a
percentage of the full scale, is used to determine which menu item is currently highlighted by the user.
The momentary action switch, SW3 is connected to a hardware interrupt line IRQ1, (P3-1, pin 19). This provides
an interrupt to handle switch presses with a minimum of CPU intervention. The switch is used to determine the
user’s selection in the current menu.
4.2.4 USB Host Connection
A USB Host connection is provided, for connection of a USB mass storage device on connector CN9. It is not
intended that this is used to supply significant power to any connected devices. It is recommended to keep the
current drawn to below 200mA.