Nathael at 01:17, 4 September 2020

2020-09-04T01:17:56Z

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	LPC micro-controlers can be programmed using the standard serial line using the ISP mode. This requires to have the <code>ISP</code> pin grounded when the LPC goes out of reset. It's often done using two micro-switches you have to manually press and release in the correct order.		LPC micro-controlers can be programmed using the standard serial line using the ISP mode. This requires to have the <code>ISP</code> pin grounded when the LPC goes out of reset. It's often done using two micro-switches you have to manually press and release in the correct order.

	As I am using the FTDI Basic module from Sparkfun to connect to the serial line, I made this circuit to use the <code>DTR</code> modem signal to easily reset and enter ISP mode.		As I am using the [https://www.sparkfun.com/products/9873 FTDI Basic module from Sparkfun] to connect to the serial line, I made this circuit to use the <code>DTR</code> modem signal to easily reset and enter ISP mode.

	[[Image:FTDIBasic.jpg\|200x200px\|center]]		[[Image:FTDIBasic.jpg\|200x200px\|center]]

Cyprien: Created page with "== FTDI Basic auto-reset for LPC == right LPC micro-controlers can be programmed using the standard serial line using the ISP mode. This requi..."

2020-09-04T01:14:52Z

Created page with "== FTDI Basic auto-reset for LPC == right LPC micro-controlers can be programmed using the standard serial line using the ISP mode. This requi..."

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== FTDI Basic auto-reset for LPC ==

[[Image:CyprienARSchemat.png|right]]

LPC micro-controlers can be programmed using the standard serial line using the ISP mode. This requires to have the <code>ISP</code> pin grounded when the LPC goes out of reset. It's often done using two micro-switches you have to manually press and release in the correct order.

As I am using the FTDI Basic module from Sparkfun to connect to the serial line, I made this circuit to use the <code>DTR</code> modem signal to easily reset and enter ISP mode.

[[Image:FTDIBasic.jpg|200x200px|center]]

How does it work?
* When the <code>DTR</code> signal goes up, the <code>Reset</code> is pulled down, putting the LPC into reset. At this moment C1 starts to discharge through R3, and if <code>DTR</code> is asserted long enough, the <code>ISP</code> pin is put low too.
* When <code>DTR</code> is back to normal, the LPC goes out of <code>Reset</code>, and if C1 is discharged enough enters <code>ISP</code> mode.

I used 2200 ohm for R3 and 47uF for C1 (which I had close), which gives a RC time of about 100ms. Note that a smaller capacitor can be used, as soon as R3 value is adapted. In my experience a 100ms <code>DTR</code> signal is enough to trigger both Reset and ISP mode, whereas a 10ms signal just triggers Reset. This is perfect!

Cons: if you want to manually push the reset button, disconnect the ISP pin as it will likely be triggered.

Here's a picture of the circuit soldered on a Vero Board (compact, some holes hold two pins together) and connected to the [[Products/DTPlug|DTPlug]] :

[[Image:CyprienARPhoto.jpg|535x400px|center]]

== Next Hack ==

User:Cyprien - Revision history

Nathael at 01:17, 4 September 2020

Cyprien: Created page with "== FTDI Basic auto-reset for LPC == right LPC micro-controlers can be programmed using the standard serial line using the ISP mode. This requi..."