Hello:
I am developing a board and shields based on nRF5340 (but this question is not really specific to nRF5340, it also applies to most other nRF5x chips). The main-board has 4 identical connectors, and I have defined a nexus node for each of the connectors. For simplicity assume each connector has 6 pins, pwr, gnd, and 4 gpios.
I have several different shields, lets say an accelerometer (i2c and irq), and a LED display with 4 LEDs (4 gpios).
I would like to plug a shield into any one of these connectors and be able to plug several of the same shields onto the main-board (lets say 3 LED shields, and one accelerometer shield).
1) My first issue is how do I write a CMakeLists.txt which tells the build system I have a LED shield plugged into CON2? I can write an overlay for the LED board plugged into CON2, but I would need 4 (slightly different) overlay files to describe the 4 places that the LED shield could be plugged in (only the nexus node name changes). I have this working. What I really want to do is have one overlay for LED shields and pass a variable into the overlay describing which connector (nexus node) it is plugged into. I think the variable could be defined in prj.conf, CMakeLists.txt or app.overlay. How can I pass a variable into the shield overlay so that the shield overlay can put the correct nexus node name into the overlay?
2) my second issue is the NRF_PSEL macro doesn't accept nexus nodes the parameters are type (TWIM_SDA, TWIM_SCL, etc.), bank (0 or 1), and port (0-31). Ideally the NRF_PSEL macro should accept a nexus node, which would be translated by the nexus node to the bank and port. Nexus node translations work fine for gpios and int-gpios. Is there a way to get NRF_PSEL to do nexus node translations?
&pinctrl {
// TODO: these should reference CON2 pins 4 and 5. not
// the pins directly on the processor. eventually
// it should be configurable for CONx
i2c1_default: i2c1_default {
group1 {
// psels = <NRF_PSEL(TWIM_SDA, &my_cpu_con2, 5)>,
// <NRF_PSEL(TWIM_SCL, &my_cpu_con2, 4)>;
psels = <NRF_PSEL(TWIM_SDA, 1, 2)>,
<NRF_PSEL(TWIM_SCL, 1, 3)>;
bias-pull-up;
};
};
};
