Management for an EV

Pimpel

A big hallo from Germany and congratulations to Propeller design.
I´m working on·a management system for an Electric vehicle called Cityel (www.cityel.de) using the Propeller.
The Sytem should control main functions of the car like blinking,brake lights a.s.o. .Also it should be able to measure the the single battery voltages (4 x 12V connected in series) the whole voltage of 48V and the Current under driving and loading the batteries. For the measurement I want to use a AD7998 which is an 8 channel 12bit ADC with I²C Interface. The·other functions·I want to realize with PCF8574AP(I still have [url=mailto:some@home]some@home[/url]).
The Voltages and the Current I want to display on a tft with AV in.
My Questions: Does anyone have an Object for the AD7998?
The PCF8574AP should work with a Voltage of 3,3V. Does it really work?
Wich OBJ should I use for I²C?

Thanks for (I hope many) answers.

Jens

PS: I´m a parallax newbie but I´m working hard to understand Spin syntax.

Mike Green

The PCF8574 does work at 3.3V. I've tried it in the past. I currently have a PCA9554 which is another I2C 8-bit I/O expander, similar to the PCF8574, that I use on a Protoboard attached to the same pins as the EEPROM (28/29). It works well. Have a look at BoeBotBasic which you can download from the Propeller Object Exchange (ww1.parallax.com/Default.aspx?tabid=65). This is a simple Basic interpreter used with a Protoboard and Parallax's BOE-BOT chassis. It happens to include support for an HM55B compass that's driven using the PCA9554. The I2C routines are written in assembly language and Spin and could be used for both the PCF8574 and the AD7998. They're not device specific and are "mid-level" in that they take care of addressing the I2C device and supplying register addressing as well as either read or write data transfers.

Post Edited (Mike Green) : 5/5/2007 10:59:48 PM GMT

Pimpel

Thanks Mike, I think this will help me (good Pseudocode).
Good night from Germany.
Time in Germany 01.36 PM :-D

Christof Eb.

Hello Jens,

you can do the adc for voltage and current directly with the propeller using sigma delta conversion. You need only 2 pins per channel.

Yes the PCF8574AP works. I have made an object to read an i2c-keyboard with PCF8574 from conrad electronics. The PCF8574AP here is supplied with 5v.

Perhaps you might want to check the power consumption of the av-display? I think other lcds will need much less power...

Best regards and good luck!
Christof

Pimpel

Thanks Christof for your answer.
Well, for the project I need more than 8 channels because the system should be upggradableup to 22 Channels. For that situation it would be unpracticle to use the I/O´s(to less). The AV Display is just used for the development. Maybe I will use another Type for series later.
U are from Germany, right? I would be positive surprised, if it would be possible to make an exchange about experiences by Email.

Would be nice to hear from U.

Best regards

Jens