Boot Mode pin selector

Farzaneh Faridi

Other Parts Discussed in Thread: SN74LVC2G66, TMUX1574, TS5A23157, TMUX1309, TS5A3357, TS5A3359, SN74LV4066A, SN74CBTLV3257

Dear members,

We need to be able to have three different ways for burning the firmware into the micro.

1- Emulator

2- RS232 driver User MODBUS

3- RS232 driver from our cloud

each of these ways has its own assigned pins in micro. I want to find a kind of chip that let me choose (or switch) between different pins while burning the firmware. In RUN MODE the connections are like:

RUN MODE MD=1

BOOT MODE MD=0 using USER MODBUS

BOOT MODE MD=0 using USER CLOUD

any suggestion would be appreciated.

Farzaneh

over 1 year ago

+1 Clemens Ladisch over 1 year ago

Guru 243820 points

When looking at the left side, the EMULATOR TDx signals just need to be disconnected; use 1:1 switches like the SN74LVC2G66.

For the RS232 USER and CLOUD signals, use 2:1 switches like the TS5A23157 or TMUX1574.

Alternatively, when looking at the right side, for the MICRO TDx signals, you can use 3:1 multiplexers like the TS5A3357 or TS5A3359. But a two-channel 4:1 device like the TMUX1309 is cheaper.

The MICRO SCIxx signals just need to be disconnected; use 1:1 switches like the SN74LVC2G66 or SN74LV4066A.

Better recommendations might be possible if we know the voltages and frequencies.

0 Rami Mooti1 over 1 year ago

TI__Mastermind 23573 points

Hey Farzaneh,

I think Clemens solutions are good! I took a look before seeing his solution and came up with same feedback as his second "Alternatively" plan. TMUX1309 would be a good cheap option and really any 1:1 switch for connnecting and disconnecting the SCI signals.
But also has he mentioned, voltage and frequency would help determine whether the solutions are viable here.

Thanks,
Rami

0 Farzaneh Faridi over 1 year ago in reply to Clemens Ladisch

Intellectual 555 points

Dear Clemens,

The signals will be connected to a micro with frequency of 12MHz and 3V3. I will take a look at what you have already suggested.

Thanks a lot

Farzaneh

0 Clemens Ladisch over 1 year ago in reply to Farzaneh Faridi

Guru 243820 points

I chose the switches mentioned above for 5 V support. They work well at 3.3 V, but you can also consider the SN74CBTLV3257 as a 4-channel 2:1 switch.

0 Farzaneh Faridi over 1 year ago in reply to Clemens Ladisch

Intellectual 555 points

Hello,

There is sth else that I need to know. Is it possible to connect serial ports (SCI signals) to Jtag ones(TDI/TDO)? They are using different protocols and I guess I can't connect them directly. Maybe I need a convertor in between.

Farzaneh

0 Clemens Ladisch over 1 year ago in reply to Farzaneh Faridi

Guru 243820 points

A switch cannot help you with this.

"SCI" is not a protocol, and I do not know which JTAG protocol you're using. A converter would be a microcontroller, but I guess you already have a microcontroller in your system. It might be possible manage the JTAG protocol with GPIOs.

0 Farzaneh Faridi over 1 year ago in reply to Clemens Ladisch

Intellectual 555 points

Dear Clemens,

I could find out that TDO/TDI ports of the microcontroller also support de SCI signals. It has been mentioned in MICRO datasheet. Now I need only to put the MUX for connecting the lines and also disconnecting them.

Thanks a lot

Farzaneh

0 Farzaneh Faridi over 1 year ago in reply to Farzaneh Faridi

Intellectual 555 points

Dear Clemens,

Just the last question to confirm that everything is correct.

I made this circuit:

where I used the analogue switches, I need them to open or close simultanously. I've thought I could use one ontrol signal for both. Is it OK? or do I need to consider more things?

Thanks

Farzaneh

+1 Clemens Ladisch over 1 year ago in reply to Farzaneh Faridi

Guru 243820 points

Yes, it's possible to use the same signal for multiple CMOS inputs.

0 Farzaneh Faridi over 1 year ago in reply to Clemens Ladisch

Intellectual 555 points

Thanks for all your support.

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Boot Mode pin selector