Iota » History » Revision 11
Revision 10 (steve-m, 02/19/2016 10:49 PM) → Revision 11/13 (laforge, 02/21/2016 08:17 AM)
h1. Iota (TWL3025) This is the Analog Baseband Chip TWL3025 It's very similar to its predecessors, the TWL3014 and TWL3016 devices. A data sheet for the TWL3014 is available from http://www.52rd.com/bbs/Detail_RD.BBS_8719_68_1_1.html but forum registration is required for download. It consists of various functions, including * ADC and DAC for the GSM baseband signals * ADC and DAC for the Voice/Audio path * DAC for APC (Automatic Power Control) * DAC for AFC (Automatic Frequency Control) * Battery Charging Controller * LDO's (Linear Power Regulators) The functions of the ABB are controlled by a register set. The register set is available through both USP and BSP. h2. External Interfaces == USP (uController Serial Port) === This is the SPI-like control interface between DBB and the TWL3025 (ABB). [[Image(Iota:twl3025_usp.png)]] h3. TSP (Timee Serial Port) It is connected to the TSP controller inside the [[HardwareCalypso]] DBB. The CLK6.5 Signal makes things a bit more complicated than we would like. The sequence of events is something like: * CLK_13M is applied continuously to TWL3025 * nTEN is in default state of high (inactive) * internal CLK6.5 is in default state low * nTEN is asserted low by TPU, some 0..65ns before CLK_13M rising edge * next CLK13M falling edge starts first CLK6.5 rising edge * every falling edge of CLK13M toggles CLK6.5 * TDR is sampled at every rising edge of CLK6.5 (including the first edge above) * 7 bits are transferred during seven rising edges of CLK6.5 * TEN stays asserted for 1 CLK13M period after last bit is transferred * TEN needs to be released before next CLK13M rising edge to prevent another transfer h3. BSP (Baseband Serial Port) This synchronous serial port is connected to the RIF (Radio [[InterFace]]) of the Calypso DBB. h3. Debug traces The chip has very tiny debug traces on a small flex-pcb around the 4 sides of the chip. Which trace goes to which ball can be seen on this scan: http://www.steve-m.de/pictures/iota_bottom.jpg
