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Dave Frederickson · (This post was last modified: 10-04-2015 07:11 AM by Dave Frederickson.)

(10-04-2015 06:48 AM)PANAMATIK Wrote:
(10-04-2015 04:10 AM)Dave Frederickson Wrote: Here's the problem. The ACT won't program when plugged into the 25. Unplugged it programs fine.

Dave

Hello Dave,

Your idea to place the USB/RS232 converter inside the calculator does not match with the constraint that the ACT 5-pin connector has to be connected AFTER the RS232 TX pin has been pulled to low level. See ACT manual description. I assume that the TX voltage level of your converter is undefined at power up and therefore you can enter the bootloader only by chance.

The sequence must be: plug in converter, then start flash update application and select COM port, then connect to ACT with TX pin before or simultanuously to VCC.

I'm sorry that this at the first glance elegant idea cannot reliably invoke the ACTs boot loader.

Bernhard

Hi Bernhard,

No, I'm following the constraints. I'm using a 3.3V FTDI cable and have followed the color-coding in my wiring to the new ACT. As you can see, Tx on the orange wire is connected to pin 5 on the USB connector and Gnd on the black wire is connected to pin 1. These are the long pins that make first contact, per the manual. When the plug is inserted fully Vcc makes contact and the LED lights every time. What happens is the downloader loses communication with the ACT at varying intervals during download. Also, that I can program the new ACT by unplugging it would indicate that the cable is wired correctly. I suspect the 25's PCB is loading down the 3.3V regulator in the cable.

There are two possibilities that I will investigate that are due to a mix up I made when ordering the cable. The bottom line is I ordered the 50mA 3.3V cable rather than the 250mA cable. My cable might not have enough current to power the new ACT and the connected circuitry. The other possibility is that I need a 5V cable. I'm not familiar with the 25's circuitry but by hooking up a bench supply I can determine which condition is causing the problem. I think Harald used a 5V cable and had no issues.

Dave