We are looking to add some PWM signals to the expansion connector. This will be valuable for robotics and other functions. We are considering two different ways to accomplish this. Our goal is to make this as non-disruptive as possible and to have a zero cost impact.
The current plan is to replace the following pins on the OMAP3530 with different pins that will not change the available functions on those expansion pins, but it will add the PWM signals to them. One side affect is that the pin muxing will change for these pins on the Rev C. There are ID pins on the REV C board that will allow the SW to identify if the board is a REV C or REV B. Based on that reading the drivers could set the pin muxing accordingly to make the pins be in the correct mode. No functionality is lost because of this change. Below are the affected signals:
EXP Pin 4
McBSP3_DX UART2_CTS GPIO_140 OMAP Pin AE6
EXP PIN 6 McBSP3_CLKX UART2_TX GPIO_142 OMAP Pin AF5
EXP PIN 8 McBSP3_
FSX UART2_RX GPIO_143 OMAP Pin AE5
EXP PIN 4 UART2_CTS McBSP3_DX gpt9_pwm_evt GPIO_144 OMAP Pin AB26
EXP PIN 6 UART2_TX McBSP3_CLKX gpt11_pwm _evt GPIO_146 OMAP Pin AA25
EXP PIN 8 UART2_RX
McBSP3_FSX gpt8_pwm_evt GPIO_147 OMAP Pin AD25
The other option would be to add pins to the expansion connector and add only two PWM signals. Those added signals in affect will only have use as a PWM signal as the other signals on those pins already exist on the expansion connector. This could also result in the connector having to move from its current location on the board.
I would like to get everyones input on this as soon as possible. We are planning to release the board in a week and I need to get this change in.