TL16C754C: Write command format

Beida Song

Part Number: TL16C754C

Tool/software:

Hi Expert,

Customer find they can read registers, but they can't write register successfully. Now they test the timing, t6s, t6h, t13w, t16s all is higher than 1us. So could you give a write command example based on logical analysis waveform? It will be a reference to customer.

3 months ago

0 Clemens Ladisch 3 months ago

Guru 316860 points

These devices are designed to be connected to the x86 ISA bus (with extra address decoding logic).

In general, you should

set the A and D lines, then (after t_6s)
pull /CS and /IOW low, then (after t_13w + t_6h)
pull /CS and /IOW high, then (after t₁₆_h)
deactivate A/D.

The figure shows the D lines being inactive for a long time, but that is not necessary.

0 Beida Song 3 months ago in reply to Clemens Ladisch

TI__Intellectual 790 points

Hi Clem,

Pls see the signal command waveform as below. Whether the D7 signal is too late to pull high? D7 should pull high before CS pull low?

0 Clemens Ladisch 3 months ago in reply to Beida Song

Guru 316860 points

During the read command, A2 changes while /CS is low. This is wrong.

During the write command, D7 changes while /CS and /IOW are low. It would be a better idea to change D first.

You are writing to and reading from different registers.

0 Beida Song 3 months ago in reply to Clemens Ladisch

TI__Intellectual 790 points

Clem,

Customer follows your suggestion and still write failure. Below is the write timing waveform. Now customer make write operation after Power On, then they will set address & CS & IOW & D[7:0] registers. Whether there need to set other registers before write operation?

0 Clemens Ladisch 3 months ago in reply to Beida Song

Guru 316860 points

These waveforms look correct, and nothing more should be needed for a write. I do not have an explanation.

0 Beida Song 3 months ago in reply to Clemens Ladisch

TI__Intellectual 790 points

Hi Clem,

Adding reset opeartion before write command, the write is successful. Do you have any programming file or user's guide for TL16C754C?

0 Clemens Ladisch 3 months ago in reply to Beida Song

Guru 316860 points

This device is designed to be compatible with the 8250 UART in the original IBM PC and with later extensions like the 16550.

en.wikibooks.org/wiki/Serial_Programming/8250_UART_Programming
intel.com/content/www/us/en/docs/programmable/683130/22-2/16550-uart-general-programming-flow-chart.html

0 BOBBY 3 months ago in reply to Beida Song

TI__Guru 73061 points

Beida,

Do you have a schematic you can provide for review?

When you are doing the write command, are you holding the RESET pin low?

-Bobby

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TL16C754C: Write command format