Re: TI-H: Re: i2c interface

To: ti-hardware@lists.ticalc.org
Subject: Re: TI-H: Re: i2c interface
From: gussie@alaska.net (Grant Stockly)
Date: Tue, 28 Apr 1998 21:33:22 -0700
Delivered-To: ti-hardware-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: ti-hardware@lists.ticalc.org

Mels desing doesn't show that very well...  Take a look at the light
flasher circut...  It is just 2 shift registers and a 4bit counter...  :)

>I'm sending this design to the Ti-Hardware list, since some may find it
>useful. I could modify it for output as well, allowing it to be used as a big
>light flasher
>
>Back in the early days of the ESF, before it even was working, mel Tsai made a
>shift register to run normal memory. It stored some bits in the register and
>used them as an address and then some more for data.
>
>The simplest way is to have it send to a shift register or a counter. A step
>counter might be better (simpler).
>
>Send a single pulse to the counter to step between devices. then read the
>input. if it's high, then it is closed, and low, it's open circuit.
>
>You can use various circuits to decode the binary output. I can't think of any
>right now, but a cheap 4 bit counter will do 16 devices!
>
>The problem is if the counter is off some how, the computer may be a device
>off, thinking say, sensor 2 was sensor 1. You just have to see what works.
>you'll have to calibrate it to make sure the thing is timed right. It should
>work fine though. only 1 send and one recieve line is needed and the only data
>is a single pulse to step to the next sensor, and the read bit is either high
>or low.
>
>A Binary to bar graph driver is OK to convert from the counter to the sensor
>select, but it has to be the single dot type, not a bar.
>
>There are various circuits you can use, but this should be fairly simple. I
>know what the stuff does, but not part numbers, so I can't give you a parts
>list though, sorry!
>
>Easier than I2C though!
>
>
>              ~           ~
>           ___|___     ___|___
>_____\____| 4-bit |___|       |__S1__
>     /    |Counter|___| 4-bit |__S2__|
>          |       |___|16 dot |__S3__|
>          |       |___| graph |__S4__|
>          |_______|   |display|__S5__|
>              |       |driver |__S6__|
>             _|_      |       |__S7__|
>              =       |       |__S8__|
>                      |       |   :  :
>                      |       |   :  :
>                      |       |__S15_|
>                      |       |__S16_|
>                      |_______|      |
>                         _|_         |
>                          =          |
>_____/_______________________________|
>     \
>
>Tx signal
>Tx:0:1:0:1:0:1:0:1:0:.......:1: 0: 1: 0: 1: 0: 1:0:1:0:1:0:...
>Sn:1:2:2:3:3:4:4:5:5:.......:14:14:15:15:16:16:1:1:2:2:3:3:...
>Sensor number
>
>Rx: sensor closed=1: sensor open=0
>
>--
>
>
>Richard Piotter
>richfile@prairie.lakes.com
>
>The Richfiles TI Hardware and BASIC web page:
>http://www.geocities.com/SiliconValley/Lakes/5081/Richfiles.html