Robot OMAPL board reconfiguration

Group 2 - Iris

Goal:

1. Separate the power source of F28335 and OMAPL, so that the robot motors won't make weird noise when the amp is on while F28335 is being flashed.

2. Study the schematics of the robot amp board, test if we can power on and off the 5V voltage regulator separately with the existing configuration.

---

Section 1

Implementation:

- Identify the power source of OMALP and F28335

- On the amp board, there are two 5V sources available. Only one of them is being used to supply 5V power to both F28335 and OMALP.

- There is a power jack coming out of the amp board is not used also.

- Need to separate the 5V supply going to OMALP (and its components) and F28335 (and its components)

- Need to add a power jack on the OMALP/F28335/camera board.

- Need to add a voltage regulator for the new 5V supply, to bring 5V down to 3.3V and use that for 3.3V components that are related to F28335.

EagleCAD work (robotomalp138_v4):
1. Schematic

- In P.1 of the schematic, power supply and voltage regulator is shown there.

- Added another power supply, named “+5V_F28335”.

- Added another voltage regulator (5V->3.3V). The output is called “+3.3V_F28335”

- In P. 5 and 6 of the schematic, everything pertains to F28335 and its related components.

- Identified all the 5V and 3.3V supplies that were related to F28335. Deleted the wires, redid the connection, and named it to be “+5V_F28335” or “+3.3V_F28335” accordingly.

2. Board

- Added the components on the board. It was placed closer to the F28335 to avoid complication of two different 5V supply going all over the board.

- DO NOT move SV 16, because it’s used as the header for the shield board.

- Deleted the original GND and +5V plane.

- Re-drew the GND plane. It covered the entire board area. Used Route2

- Drew the +5V_F28335 plane using the polygon tool on Route 3. It covered all the components that uses +5V_F28335 supply

- Drew another +5V supply plane on Route 3. Only covered the other components using +5V.

- Edited the design rule based on the on the same specification as robot_omalpSOM138_v3. [Basically leave everything as default, and change the Layer tab only.]

- In Design Rule -> the layer tab, “Setup”, change it from (1*16) to (1*2*3*16), as the board was a 4-layer board.

- Ran auto-router. Disable optimizer for the first run.

- When the auto-router completed the routing, re-ran the auto-router again, set all the Optimizers to be active.

- Prepared the CAM files based on the instruction on the Lab4 EAGLE tips. NOTE: this is a 4 layer board, so use “4layerwithsilkscreen.cam” instead.

- Submit for a PCB check at www.4pcb.com

3. PCB check

- Referred to the instruction on Lab4 again. However, since the board was a 4-layer board, couple more files were needed:

i. *.g02 Inner Copper; Positive; Layer 2

ii. *.g03 Inner Copper; Positive; Layer 3

- Changed “LayerCount” to 4.

- “Inner Copper Wt” to 1oz

- Keep the rest as default.

Figure 1: New board after routing

Section 2

Implementation:

- The 5V regulators on the amp board are currently powered by the same source. According to the data sheet, a transistor should be used to turn the 5V regulator on or off at pin 1 (remote on/off).

- The current board already has the transistor (BS138) for each of the regulators. They receive the same input, but they are not connected to the 5V regulator.

- As per instruction on the data sheet, a MOSFET should always be used to turn on/off the regulator

- To tests if we can turn on and off the regulator separately, the homework board was used. The on off of the TIP122 transistor on the board was controlled by the GPIO pins. The collector pin was connector to the Pin1 (remote on/off) of the regulator.

- The output of the voltage regulator was tested with a digital multimeter. TIP122 was able to be used as on/off control of each of the voltage regulator.

Data Sheet: PT4142-Texas-Instruments-datasheet-149538.pdf

---