What I do is the following: Have the RESET input unconnected. When you power up, this makes an internal reset during the power up, and that's all you need. Then configure your registers using the sequences described in the manual. Then do not touch the RESET any more.
Thank you Stefan for replying!
I have still the RESET issue in mind: how would you suggest to reset properly the DRS? Is there a particular procedure to follow instead of just sending a negative pulse to the RESET pin? Is it preferable to turn the DRS off and then restart?
1. WRITE SHIFT register and CONFIG registers are initialized to "1" on power up, but if you want to change that, use A0-A3 etc. as you indicated.
2. If you address the READ SHIFT register by applyin "1011" to A0-A3, the input of the register is connected to SRIN. So in fig. 11, you apply 1023x"0" plus 1x"1", which effectively clears the register and keeps one "1" at the last position, so on the next rising clock this gets shifted into position #0. If you do the readout, and NOT addresing the READ SHIFT register, then the input of that register is connected to it's output internally. Therefore the single "1" keep rotating on every 1024 clock cycles.
Hej Stefan! Thank you for your answer!
Just to be sure to have understood properly:
1. Using the RESET line should be avoided. And in any case, the CONFIG register and the WRITE SHIFT register need to be initialized "by hand" using the A0-A3, SRCLK and SRIN pins. Is it correct?
2. Doing the procedure shown in Figure 11 will always inject a "1" in cell #0 of the READ SHIFT register, regardless if (before starting the procedure) there was a "1" in any other cell, right?
Using the RESET line to reset registers is not a good idea since it can have some bad side-effects. The READ SHIFT register is NOT affected by RESET, so you have to inititialize these registers differently. To set a "1"-value at a defined position, you have to follow figure 11 in the data sheet. Once you executed that, your "1" is always at the same posiiton (namely cell #0), so after 1024 clock cycles you arrive at the same state, and do not have to re-do fig. 11 again.
I have some questions regarding what happens to some DRS registers in some scenarios:
1. How are the registers affected by a RESET? According to the data sheet all the CONFIG REGISTER bits are initilialized to 1. But what about the WRITE SHIFT and the READ SHIFT registers? Are they affected somehow after a RESET has been applied?
2. Suppose the DRS is happily running and I have done some readouts in ROI mode, so that the only "1"-value bit in the READ SHIFT register is in a random position. If now I want to execute a FULL READOUT, should I use the procedure explained in the data sheet (figure 11) for the FULL READOUT mode? or is this procedure useless since my "1"-value bit is already set somewhere in the READ SHIFT register and therefore a ROI readout of 1024 cells would be the solution (and getting the initial position from the SROUT pin)?
Thanks a lot!
Have a nice day!