From: Harold Hallikainen <harold@mai.hallikainen.org>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Sender: "piclist-bounces@mit.edu" <piclist-bounces@mit.edu>
Date: Sun, 14 Mar 2021 12:30:59 -0700
Subject: {Spam?} Re: [PIC] 1 Controller and 18 Peripheral PICs
Thread-Topic: {Spam?} Re: [PIC] 1 Controller and 18 Peripheral PICs
Thread-Index: AdcZCdbEhKigVJ/FQbWUatzTGYkBZw==
Message-ID: <433d8321136504b648f58b2840db147b.squirrel@mai.hallikainen.org>
References: <24a1eea7-dbb8-da98-309e-cd4fb87bd4d4@gmail.com>
	<6d88a2e449f9c633a0ca57efdc178c97.squirrel@mai.hallikainen.org>
	<f1b53c87-c3c6-61a2-0825-ba44d9f227df@gmail.com>
	<CAAV7uvXOoEkERqrj6cUeprm0dwL0-A8sGbJerZxEDe9EktSLVw@mail.gmail.com>
In-Reply-To:
 <CAAV7uvXOoEkERqrj6cUeprm0dwL0-A8sGbJerZxEDe9EktSLVw@mail.gmail.com>
Reply-To: Microcontroller discussion list - Public. <piclist@mit.edu>
Accept-Language: en-US
X-MS-Exchange-Organization-SenderIdResult: Pass
X-MS-Exchange-Organization-PRD: mit.edu
X-MS-TNEF-Correlator:
received-spf: Pass (protection.outlook.com: domain of mai.hallikainen.org
	designates 208.80.15.114 as permitted sender)
	receiver=protection.outlook.com; client-ip=208.80.15.114;
	helo=mailscanner.virtbiz.com;
dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
	d=mitprod.onmicrosoft.com; s=selector2-mitprod-onmicrosoft-com;
	h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck;
	bh=d+YEc9hgQNPvHtmQRKgcP2/9mzkrEeGHg1ScdNGRBG8=;
	b=IMW8QhqKqclhRNrba3CU9veXybWggb2FRbdejpLA6IyReryJWVdBXQvwh0E0m9CIRfxVKoKe0x4UmEU8/nRv08uGqwd4KKhmzpjkmOhgvvAR6HDz7erisDVDypajBpFvL+f4QZ6aW9HLKq+8Nn9zV521rRSrrqIKSFBNc5PcMts=
authentication-results: spf=pass (sender IP is 208.80.15.114)
	smtp.mailfrom=mai.hallikainen.org; mit.edu;	dkim=none (message not signed)
	header.d=none;mit.edu; dmarc=permerror action=none
	header.from=mai.hallikainen.org;
user-agent: SquirrelMail/1.4.22-5.el6
errors-to: piclist-bounces@mit.edu
list-id: "Microcontroller discussion list - Public." <piclist.mit.edu>
list-post: <mailto:piclist@mit.edu>
x-beenthere: piclist@mit.edu
x-mailman-version: 2.1.6
x-authentication-warning: mai.hallikainen.org: apache set sender to
	harold@mai.hallikainen.org using -f
x-spam-status: Yes
x-greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2
	(mailscanner.virtbiz.com [208.77.216.252]);	Sun, 14 Mar 2021 14:31:02 -0500
 (CDT)
x-topics: [PIC]
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0


> Hi Jim, have you considered a series of WS2801 or WS2811 serial controlle=
d
> ICs, their PWM output connected to a simple amp to handle your higher
> current LEDs?
> These controllers are widely used, have built-in PWM control of 3 LEDs
> each
> package, and can be strung in a serial series.  You can effectively
> control
> a large array of LEDs with a single microcontroller pin tied to the SPI
> peripheral output.
>

Those are interesting chips. I especially like the buffered clock output
so you can cascade chips using series source termination and not have to
worry about reflections. The serial protocol is interesting. It appears
they use a delay of greater than 500us to latch the serial data. That's a
clever way of getting rid of a chip select to latch the data.

On increasing the current output, I remember a current mirror FET years
ago, perhaps from Motorola. I can't find it now, but, as I recall, the die
included something like 101 FETS with 100 of them in parallel and 1 with
the source and gate in parallel. If the FET was driven such that the drain
current was a specific value on the lone FET, it would be 100 times that
on the other FETs. Anyone remember that part? Is it still available?

Harold
https://w6iwi.org



--=20
FCC Rules Updated Daily at http://www.hallikainen.com
Not sent from an iPhone.
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.