uart
I am curently working on a project where a MCU got only one UART port available, however I need to run two peripherals with UART interface (not simultaneously) so I was wondering if I can connect two peripherals UARTs on the same UART of the MCU while playing with enabling and disabling the peripherals one by one for communicating with the MCU?
Your feedbacks and recommendation are appreciated about this situation
Regards
Digikey has excellent selection tools for its components. You can select on package, manufacturer, ADC, and other features. (Odd that memory size doen't seem to be important.)
I found 143 parts matching your requirements. The ATmega48P is 1.76 dollar in 1s and has 4 kB of Flash. The ATmega88P and ATmega168P are the same, but with 8 kB and 16 kB Flash, resp (same datasheet).
Okay, we have some info on the sensors.
This should be doable with one of the newer dsPIC33Fs. As @gbarry correctly notes, they have variants that can do 4 channel simultaneous sampling (i.e. they have 4 sample and holds)
I am currently using one of these for some experimentation, the dsPIC33FJ64GP802. It's an impressive little chip, much better than the older dsPIC30F4011s. It runs at up to 40 MIPs, and has an 8-channel DMA which you can use for the ADC and other peripherals, so getting your timing within spec should be not so hard. The DMA makes life much easier, you can use it plus interrupts to save your main loop as much as time as possible.
You also have 2 UARTs, and 4 capture/compares (for the quad encoder) plus 5 timers.
You are missing 1 UART, so you will neither need to bit bang or add an external UART IC if you can't find a variant with more than 2 UARTs.
There are a few versions to choose from, the one I linked to is one of the smaller ones memory wise (I was mainly interested in the ADC and audio DAC plus DMA for audio ideas prototyping), so have a browse through all the options.
Best Answer
Since you need to be connected to only one device at a time, you could use a multiplexer to switch between the two chips, like the NX3L2467:
You only need a DPDT switch; this is a 4PDT one so you're only using half of the circuit. But all of the DPDT switches I found had very unfriendly packages to work with such as VQFN, BGA etc. This part comes in a 16-pin TSSOP package; not as nice as a DIP to work with but doable. You can get TSSOP16 to DIP adapters. It also has a very low on-resistance (0.5Ω). It will work off of 3.3V which I assume is your supply voltage.