I2C Display Assistance

[atc005]

I am trying to connect Adafruit I2C 4 digit 7 segment displays using Pins 14 for SCL and 15 for SDA on the Prop-2.  I have been reviewing Stampworks and the N&V article about I2C but I am having issues with the slave addresses.  The addresses I have on each display is 0x70 and 0x74, but I seem to have issues with trying to talk to the devices.

Has anyone used these displays before with the prop-2 and if so, do you have any sample code I could review?

[JonnyMac]

I've used them with the HC-8+ (Propeller), and I wrote StampWorks, so I should be able to translate the code. Give me a little time.

[JonnyMac]

Here is a demo for you to start with: it displays a running counter on the 7-segment display. I used the low-level routines from my StampWorks programs, then created a couple medium-level routines for the display.

The Adafruit 7-segment display is tricky for two reasons:
1) It uses the HT16K33 driver which has 16-segments per digit (only the lower 8 bits are used)
2) It maps the colon to digit 2 in the display, so you have to code around that

No matter what, do study the HT16K33 documentation. It is a bit difficult at first, but reviewing it with the code may make things a little easier.

Be mindful of the connections -- you must disconnect the ULN from pins used the SCL and SDA. On the Prop-2 I prefer pins 14 and 15 for this connection.

If you ever move to the HC-8+, I have objects that encapsulate all the features of the HT16K33, and I have variants for the 7- and 14-segment displays.

PS: Adafruit docs are Arduino-centric, hence addresses are 7-bit (without read/write bit). In my program you'll find this:

Code Select Expand

HT16K33         CON     %11100000               ' base device ID
DevAddr         CON     %000                    ' %000..111

SlaveID         CON     %11100000               ' manual build

If you take my base ID (%11100000) and shift it right by one (as the Arduino does), you get %01110000 which is $70.