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Discussion Groups | 68HC12 | BDM mode and ccts, flash voltages, AD questions
Join our technical discussions about Freescale Microcontrollers: M68HC12. (Freescale Semiconductor is a Subsidiary of Motorola).
BDM mode and ccts, flash voltages, AD questions - Lewis, Bob - Jun 10 12:52:00 2002
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Hi Our MCU is the M68dg9128a eval brd, and works as long as the BDM cable is plugged in (the code is fully rom'd); how do we set this up to run without the bdm cable? Is there a software change necessary; we are using the Imagecraft ICC12 V6.13 c compiler and the supplied startup code, unmodified. We are designing a prototype board and are not sure what to do with the following signals. 1) How do we connect up the BKGD feature to our board? We have BDMIP and BDMOP also to account for. 2) We need to program the flash via the ComPod (debug module from Electonikladen), - what would be the way that VFP connected? Is this a 5v signal or do we have to use 12v. I thought that the 128a used 5v to program the flash, hence the "a" designation. But all the literature on the dg128a on the Motorola site talks about needing 12v, so I am lost on this. - is anyone able to provide us with an example cct for this please? 3) Should we pull the RXCAN and/or TXCAN signal high/low with a pullup/pulldown resistor? We are not using the RXCAN, TXCAN ccts. 4) For VDDAD, is this used to allow a separate voltage for the on micro A/D's? If so what is the voltage typically used for these A/D signals. If so how should it be connected? Should it be connected to VCC or +12V. 5) Do we need to use XFC; we will use a canned oscillator initially, then perhaps switch to the pll for cost savings (as in your posts) until then, should XFC be allowed to float? 6) What should we do with the signals such as VSSPLL, VDDPLL if we are using a canned oscillator; should they be tied to VCC and gnd? Thank you for the help. Bob Lewis Mgr. Process Computer Systems Tilbury and Tehachapi Plants Tilbury Cement Ltd (604) 946-0411 office, (604) 952-5651 direct line PO Box 950 (604) 946-2214 fax 7777 Ross Road (604) 727-1244 cell (forwards to pager, on no answer) Delta, BC V4G 1B8 (888) 820-5852 pager (major cities) |
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RE: BDM mode and ccts, flash voltages, AD questions - Lewis, Bob - Jun 10 15:12:00 2002
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Thank you Doron, this gives us a reference point now.
Bob
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Re: BDM mode and ccts, flash voltages, AD questions - Doron Fael - Jun 10 15:44:00 2002
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Bob, See some answers bellow. Doron HC12 In Circuit Emulators Nohau Corporation www.nohau.com At 10:52 AM 6/10/2002 -0700, you wrote: Hi You must initialize all your RAM based or register based variables explicitly in your code. You cannot rely on the debugger to load them for you. 1) How do we connect up the BKGD feature to our board? BKGD is connected to VCC to select Normal operating modes, and to GND to select Special operating modes. Most users are using Normal modes, and an HC12 internal pull-up resistor on the BKGD pin exist, so no connection is required for Normal modes. If you don't trust the internal pull up, you can add a 4.7K pull up on your board. You also need to consider PE6 and PE5 which also set the operating mode after Reset. During Reset PE5 and PE6 have internal pull-down resistors that default the HC12 to single-chip modes (Special or Normal based on the BKGD). If you need to bring the HC12 in a non Single-Chip mode after Reset, or has logic driving PE5 and PE6, you need to make sure their state during Reset brings your HC12 to the desired operating mode after Reset. 2) We need to program the flash via the ComPod (debug module from No 12V is needed to program or erase the Dx128A parts. 12V is only required for the Dx128 non A parts. 3) Should we pull the RXCAN and/or TXCAN signal high/low with a I don't think you need to do that, but I'm not a CAN expert. I know it doesn't cause any funny behavior if you leave these pins floating. 4) For VDDAD, is this used to allow a separate voltage for the on micro Absolutely not 12V!!! Typically VDDA is +5V, and is allowed to deviate from VDDX and VDD only by 300mV or so. VDDA and VSSA are to supply a clean low current analog voltage to the A/D converter, free of spikes that are typically found on the digital VDDX and VDD supply pins. 5) Do we need to use XFC; we will use a canned oscillator initially, then XFC can float as long as you don't use the HC12 PLL. You must connect two capacitors and a resistor to XFC as soon as you want to use thew HC12 PLL. 6) What should we do with the signals such as VSSPLL, VDDPLL if we are using VSSPLL should be tied to GND always. VDDPLL could be tied to GND when you are not using the HC12 PLL. I could be connected to +5V too. If you are using a canned oscillator it does not matter for you. In order to use the HC12 PLL, you must connect VDDPLL to +5V. Thank you for the help. Bob Lewis |
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Re: BDM mode and ccts, flash voltages, AD questions - Sam Laur - Jun 11 2:35:00 2002
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"Lewis, Bob" wrote: > Our MCU is the M68dg9128a eval brd, and works as long as the BDM > cable is plugged in (the code is fully rom'd); how do we set this > up to run without the bdm cable? Is there a software change > necessary; we are using the Imagecraft ICC12 V6.13 c compiler > and the supplied startup code, unmodified. Here's what I found out (D60A and ICC12 v6.13 and even ComPod) : The startup code seems to hang when run without the pod, right after the instruction to disable COP. Can't be 100% certain about this, because it runs quite well with the pod... My solution was to write my own startup routine: void _HC12Setup(void) { COPRST = 0x55; // First disarm COP COPRST = 0xAA; COPCTL &= ~0x07; // Then disable COP completely } Whatever it does, it's working now. The standard startup code only does the COPCTL three lower bits. > 2) We need to program the flash via the ComPod (debug module from > Electonikladen), > - what would be the way that VFP connected? Is this a 5v signal or > do we have to use 12v. This was answered already, but our experience with the D60A seems to suggest the same; no 12V needed, you can just leave VFP connected to +5V. |
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