3.4.5.2. PRU Cape Hardware User Guide¶

3.4.5.2.1.1. Description¶

The PRU Cape is a test, development, and evaluation module system that enables developers to write software and develop hardware around the PRU subsystem. Examples of basic I/O such as push buttons and LEDs as well as more complicated examples such as audio and 1-Wire for temperature sensing are available on this cape to showcase what the PRU can accomplish in terms of inputs and outputs.

The following sections give more details regarding the PRU Cape.

3.4.5.2.1.2. EVM System View¶

The PRU Cape is shown below.

3.4.5.2.3.1. System Board Diagram¶

The system block diagram of the PRU Cape are shown in the below Figures.

PRU Cape Board Layout:

PRU Cape Functional Block Diagram

3.4.5.2.3.2. Signals Used¶

Table: Table 1. Signals Used

3.4.5.2.4.1. Audio¶

The audio portion of the PRU Cape is composed of a Dual 8-bit DAC (DAC082S085) and a dual 105 mW Amplifier (LM4808). The output is then sent to a 3.5 mm Audio jack with a max pk-pk of .89V, following the consumer standard.

3.4.5.2.4.2. EEPROM¶

The EEPROM on the PRU cape is the CAT24C256WI-G EEPROM 256Kb I2C SOIC8, and has an attached DIP switch to manipulate the I2Caddress. The first 78 bytes hold a file that the Beagle Bone Black will read to identify the cape, the rest of the EEPROM is available for use.

3.4.5.2.4.3. eCAP¶

These pins are brought out on the board that connect to the eCAP0 PWM0 IN to allow use of the PRU Subsystem’s eCAP IP.

3.4.5.2.4.4. LCD¶

The LCD screen is on a duaghter board with its own built in controller, model number  NHD-0208AZ-RN-YBW-33V. The LCD is connected to the PRU Cape throught the 2x8 female header in the middle of the cape. The LCD is a 2x8 Character display operating at 3.3V.

3.4.5.2.4.5. LEDs¶

The PRU Cape has 7 surface mounted LEDs, including Red, Orange, Blue and Green colors. There are 4 LEDs connected to PRU0 output, and 3 connected to PRU1 output.

3.4.5.2.4.6. Switches¶

The PRU Cape has two pushbutton switches connected to PRU0 inputs.

3.4.5.2.4.7. Temperature Sensor¶

The temperature sensor is a MAX31820 ambient temperature sensor, with a 1-Wire interface. Two pins are tied together from the PRU to create input and output on a single wire.

3.4.5.2.4.8. Test Space¶

The test space is a set of 150 through holes (15x10). There is no connection between the through holes and is meant for attaching a through hole component, wheather it be an IC or passive to test with the PRU or any signal that can be accessed through the Cape Headers.

3.4.5.2.4.9. UART¶

There is one RS-232 connector (DB9 male) on the PRU Cape. The MAX3232ECD is the line driver/receiver.

3.4.5.2.4.10. Legal¶

• Standard Terms and Conditions for Evaluation Modules