Other than level shifting from 3 to 5v, what does the I2C mux do that simply connecting the devices to a shared bus does not?
On Sat, Nov 19, 2022, 19:25 <
g8ptn@...> wrote:
Hi Mark and Jim,
I only have a basic block diagram (see attached) and a few notes below. If you have any further questions I will try and cover them.
Each function is built on bread board and/or copper clad. The functions currently built are as follows:
- 12V reverse polarity protection and inrush current limit.
- VI monitoring and 5V PSU.
- D1 Mini (ESP8266) and I2C Multiplexer.
- IO Expanders and Fan control. Provision is provided for up to 16 IO pins (currently 6 are being used).?
- RX Audio
- TX Audio
?
The majority of the peripherals are connected via I2C. The interfaces are point to point to try and minimise RF noise.
Two rotary encoders are provisioned, one for volume control and the other for general use such as setting of parameters.
The rotary encoders use "I2C Encoder Mini" modules which provide an I2C interface. This minimises the IO and processing overhead on the D1 Mini MCU.
The INT signal from the rotary encoders is polled by the D1 Mini MCU, and if active the status of the rotary encoders is then read via I2C.
The digital potentiometers are connected via a SPI bus. This allows control of the following parameters:
- Noise gate and compression ratio on the RX SSM2167 module
- Volume level driving the LM386 audio amplifier
- Noise gate and compression ratio on the TX SSM2167 module
- Mic level driving the uBITX MIC input
The forward and reflected voltages from the RF Stockton bridge are connected to an ADS1115 ADC. The Pfwd, Pref and VSWR values are calculated by the D1 Mini MCU.
The RMS level detector from the receive SSM2167 (AVG CAP) is buffered and amplified before being passed to the uBITX Raduino analogue S-Meter input.
The firmware for the ESP8266 uses the Arduino IDE and appropriate libraries for the devices and MQTT client support.
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73, Dave
Mark Phillips