I will most likely fashion another panel a little bit larger that will have room for more buttons as well as the rotary encoder at which time the current tuning pot will become the speed control for a keyer. I have located some scrap aluminum, so I think it is the next best step.
Hello Jeff,
ReplyDeleteAre you using a I2C Expander for the LCD ? Is it supporting the 20x4 LCD version ?
The i2c expander is not necessary in my arrangement for the LCD. The LCD and the expander share the i2c bus between the ATMega382 and the expander. This is a 5 volt bus. The Si570 devices are on separate channels behind the expander. This provides the ability to address each Si570 which have the same i2c address separately by just selecting the channel the one you want is on. It also provides a voltage level shift to 3V3 as required by the Si570. I put any i2c device at 5V directly on the i2c bus connected to the ATMega328 as no voltage level shift is needed. Anything requiring 3V3 can go on either of the first two channels of the expander. I have two additional channels that are not currently used. Any voltage level from 1.8 to 5V (or more) can be used on the extra channels.
ReplyDeleteOnce you select a channel, you can see any device on the input to the expander as well as on the channel selected. So, I can set the channel during setup to channel 1 and I need do nothing else to see the LCD or Si570. If you don't use the second Si570, no further action is required.
The expander is very non-intrusive. It changes channels at quiet times on the bus so there are no runt pulses or noise created on any of the buses.